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  • Coupling/Cohesion

    - by user559142
    Hi All, Whilst there are many good examples on this forum that contain examples of coupling and cohesion, I am struggling to apply it to my code fully. I can identify parts in my code that may need changing. Would any Java experts be able to take a look at my code and explain to me what aspects are good and bad. I don't mind changing it myself at all. It's just that many people seem to disagree with each other and I'm finding it hard to actually understand what principles to follow... package familytree; /** * * @author David */ public class Main { /** * @param args the command line arguments */ public static void main(String[] args) { // TODO code application logic here KeyboardInput in = new KeyboardInput(); FamilyTree familyTree = new FamilyTree(in, System.out); familyTree.start(); } } package familytree; import java.io.PrintStream; /** * * @author David */ public class FamilyTree { /** * @param args the command line arguments */ private static final int DISPLAY_FAMILY_MEMBERS = 1; private static final int ADD_FAMILY_MEMBER = 2; private static final int REMOVE_FAMILY_MEMBER = 3; private static final int EDIT_FAMILY_MEMBER = 4; private static final int SAVE_FAMILY_TREE = 5; private static final int LOAD_FAMILY_TREE = 6; private static final int DISPLAY_ANCESTORS = 7; private static final int DISPLAY_DESCENDANTS = 8; private static final int QUIT = 9; private KeyboardInput in; private Family family; private PrintStream out; public FamilyTree(KeyboardInput in, PrintStream out) { this.in = in; this.out = out; family = new Family(); } public void start() { out.println("\nWelcome to the Family Tree Builder"); //enterUserDetails(); initialise(); while (true) { displayFamilyTreeMenu(); out.print("\nEnter Choice: "); int option = in.readInteger(); if (option > 0 && option <= 8) { if (quit(option)) { break; } executeOption(option); } else { out.println("Invalid Choice!"); } } } //good private void displayFamilyTreeMenu() { out.println("\nFamily Tree Menu"); out.println(DISPLAY_FAMILY_MEMBERS + ". Display Family Members"); out.println(ADD_FAMILY_MEMBER + ". Add Family Member"); out.println(REMOVE_FAMILY_MEMBER + ". Remove Family Member"); out.println(EDIT_FAMILY_MEMBER + ". Edit Family Member"); out.println(SAVE_FAMILY_TREE + ". Save Family Tree"); out.println(LOAD_FAMILY_TREE + ". Load Family Tree"); out.println(DISPLAY_ANCESTORS + ". Display Ancestors"); out.println(DISPLAY_DESCENDANTS + ". Display Descendants"); out.println(QUIT + ". Quit"); } //good private boolean quit(int opt) { return (opt == QUIT) ? true : false; } //good private void executeOption(int choice) { switch (choice) { case DISPLAY_FAMILY_MEMBERS: displayFamilyMembers(); break; case ADD_FAMILY_MEMBER: addFamilyMember(); break; case REMOVE_FAMILY_MEMBER: break; case EDIT_FAMILY_MEMBER: break; case SAVE_FAMILY_TREE: break; case LOAD_FAMILY_TREE: break; case DISPLAY_ANCESTORS: displayAncestors(); break; case DISPLAY_DESCENDANTS: displayDescendants(); break; default: out.println("Not a valid option! Try again."); break; } } //for selecting family member for editing adding nodes etc private void displayFamilyMembers() { out.println("\nDisplay Family Members"); int count = 0; for (FamilyMember member : family.getFamilyMembers()) { out.println(); if (count + 1 < 10) { out.println((count + 1) + ". " + member.getFirstName() + " " + member.getLastName()); out.println(" " + member.getDob()); out.println(" Generation: " + member.getGeneration()); } else { out.println((count + 1) + ". " + member.getFirstName() + " " + member.getLastName()); out.println(" " + member.getDob()); out.println(" Generation: " + member.getGeneration()); } count++; } } private int selectRelative() { out.println("\nSelect Relative"); out.println("1. Add Parents"); out.println("2. Add Child"); out.println("3. Add Partner"); out.println("4. Add Sibling"); out.print("\nEnter Choice: "); int choice = in.readInteger(); if (choice > 0 && choice < 5) { return choice; } return (-1); } private void addFamilyMember() { int memberIndex = selectMember(); if (memberIndex >= 0) { FamilyMember member = family.getFamilyMember(memberIndex); int relative = selectRelative(); if (relative > 0) { out.println("\nAdd Member"); //if choice is valid switch (relative) { case 1: //adding parents if (member.getFather() == null) { FamilyMember mum, dad; out.println("Enter Mothers Details"); mum = addMember(relative, "Female"); out.println("\nEnter Fathers Details"); dad = addMember(relative, "Male"); member.linkParent(mum); member.linkParent(dad); mum.linkPartner(dad); mum.setGeneration(member.getGeneration() - 1); dad.setGeneration(member.getGeneration() - 1); sortGenerations(); } else { out.println(member.getFirstName() + " " + member.getLastName() + " already has parents."); } break; case 2: //adding child if (member.getPartner() == null) { FamilyMember partner; if (member.getGender().equals("Male")) { out.println("Enter Mothers Details"); partner = addMember(1, "Female"); } else { out.println("Enter Fathers Details"); partner = addMember(1, "Male"); } //create partner member.linkPartner(partner); partner.setGeneration(member.getGeneration()); out.println(); } out.println("Enter Childs Details"); FamilyMember child = addMember(relative, ""); child.linkParent(member); child.linkParent(member.getPartner()); child.setGeneration(member.getGeneration() + 1); sortGenerations(); break; case 3: //adding partner if (member.getPartner() == null) { out.println("Enter Partners Details"); FamilyMember partner = addMember(relative, ""); member.linkPartner(partner); partner.setGeneration(member.getGeneration()); } else { out.println(member.getFirstName() + " " + member.getLastName() + " already has a partner."); } break; case 4: //adding sibling FamilyMember mum, dad; if (member.getFather() == null) { out.println("Enter Mothers Details"); mum = addMember(1, "Female"); out.println("\nEnter Fathers Details"); dad = addMember(1, "Male"); member.linkParent(mum); member.linkParent(dad); mum.linkPartner(dad); mum.setGeneration(member.getGeneration() - 1); dad.setGeneration(member.getGeneration() - 1); sortGenerations(); out.println("\nEnter Siblings Details"); } else { out.println("Enter Siblings Details"); } FamilyMember sibling = addMember(relative, ""); //create mum and dad mum = member.getMother(); dad = member.getFather(); sibling.linkParent(mum); sibling.linkParent(dad); sibling.setGeneration(member.getGeneration()); break; } } else { out.println("Invalid Option!"); } } else { out.println("Invalid Option!"); } } private int selectMember() { displayFamilyMembers(); out.print("\nSelect Member: "); int choice = in.readInteger(); if (choice > 0 && choice <= family.getFamilyMembers().size()) { return (choice - 1); } return -1; } private FamilyMember addMember(int option, String gender) { out.print("Enter First Name: "); String fName = formatString(in.readString().trim()); out.print("Enter Last Name: "); String lName = formatString(in.readString().trim()); if (option != 1) { //if not adding parents out.println("Select Gender"); out.println("1. Male"); out.println("2. Female"); out.print("Enter Choice: "); int gOpt = in.readInteger(); if (gOpt == 1) { gender = "Male"; } else if (gOpt == 2) { gender = "Female"; } else { out.println("Invalid Choice"); return null; } } String dob = enterDateOfBirth(); lName = formatString(lName); FamilyMember f = family.getFamilyMember(family.addMember(fName, lName, gender, dob)); f.setIndex(family.getFamilyMembers().size() - 1); return (f); } private String formatString(String s){ String firstLetter = s.substring(0, 1); String remainingLetters = s.substring(1, s.length()); s = firstLetter.toUpperCase() + remainingLetters.toLowerCase(); return s; } private String enterDateOfBirth(){ out.print("Enter Year Of Birth (0 - 2011): "); String y = in.readString(); out.print("Enter Month Of Birth (1-12): "); String m = in.readString(); if (Integer.parseInt(m) < 10) { m = "0" + m; } m += "-"; out.print("Enter Date of Birth (1-31): "); String d = in.readString(); if (Integer.parseInt(d) < 10) { d = "0" + d; } d += "-"; String dob = d + m + y; while(!DateValidator.isValid(dob)){ out.println("Invalid Date. Try Again:"); dob = enterDateOfBirth(); } return (dob); } private void displayAncestors() { out.print("\nDisplay Ancestors For Which Member: "); int choice = selectMember(); if (choice >= 0) { FamilyMember node = family.getFamilyMember(choice ); FamilyMember ms = findRootNode(node, 0, 2, -1); FamilyMember fs = findRootNode(node, 1, 2, -1); out.println("\nPrint Ancestors"); out.println("\nMothers Side"); printDescendants(ms, node, ms.getGeneration()); out.println("\nFathers Side"); printDescendants(fs, node, fs.getGeneration()); } else { out.println("Invalid Option!"); } } private void displayDescendants() { out.print("\nDisplay Descendants For Which Member: "); int choice = selectMember(); if (choice >= 0) { FamilyMember node = family.getFamilyMember(choice); out.println("\nPrint Descendants"); printDescendants(node, null, 0); } else { out.println("Invalid Option!"); } } private FamilyMember findRootNode(FamilyMember node, int parent, int numGenerations, int count) { FamilyMember root; count++; if (node.hasParents() && count < numGenerations) { if (parent == 0) { node = node.getMother(); root = findRootNode(node, 1, numGenerations, count); } else { node = node.getFather(); root = findRootNode(node, 1, numGenerations, count); } return root; } return node; } private int findHighestLeafGeneration(FamilyMember node) { int gen = node.getGeneration(); for (int i = 0; i < node.getChildren().size(); i++) { int highestChild = findHighestLeafGeneration(node.getChild(i)); if (highestChild > gen) { gen = highestChild; } } return gen; } private void printDescendants(FamilyMember root, FamilyMember node, int gen) { out.print((root.getGeneration() + 1) + " " + root.getFullName()); out.print(" [" + root.getDob() + "] "); if (root.getPartner() != null) { out.print("+Partner: " + root.getPartner().getFullName() + " [" + root.getPartner().getDob() + "] "); } if (root == node) { out.print("*"); } out.println(); if (!root.getChildren().isEmpty() && root != node) { for (int i = 0; i < root.getChildren().size(); i++) { for (int j = 0; j < root.getChild(i).getGeneration() - gen; j++) { out.print(" "); } printDescendants(root.getChild(i), node, gen); } } else { return; } } //retrieve highest generation public int getRootGeneration(){ int min = family.getFamilyMember(0).getGeneration(); for(int i = 0; i < family.getFamilyMembers().size(); i++){ min = Math.min(min, family.getFamilyMember(i).getGeneration()); } return Math.abs(min); } public void sortGenerations(){ int amount = getRootGeneration(); for (FamilyMember member : family.getFamilyMembers()) { member.setGeneration(member.getGeneration() + amount); } } //test method - temporary private void initialise() { family.addMember("Bilbo", "Baggins", "Male", "23-06-1920"); } } package familytree; import java.util.ArrayList; import java.util.Date; /** * * @author David */ public class Family { //family members private ArrayList<FamilyMember> family; //create Family public Family() { family = new ArrayList<FamilyMember>(); } //add member to the family public int addMember(String f, String l, String g, String d) { family.add(new FamilyMember(f, l, g, d)); return family.size()-1; } //remove member from family public void removeMember(int index) { family.remove(index); } public FamilyMember getFamilyMember(int index) { return family.get(index); } //return family public ArrayList <FamilyMember> getFamilyMembers() { return family; } public void changeFirstName(int index, String f) { family.get(index).setFirstName(f);//change to setfirstname and others } public void changeLastName(int index, String l) { family.get(index).setLastName(l); } public void changeAge(int index, int a) { family.get(index).setAge(a); } public void changeDOB() { //implement } } package familytree; import java.util.ArrayList; import java.util.Collections; /** * * @author David */ public class FamilyMember extends Person { private FamilyMember mother; private FamilyMember father; private FamilyMember partner; private ArrayList<FamilyMember> children; private int generation; private int index; //initialise family member public FamilyMember(String f, String l, String g, String d) { super(f, l, g, d); mother = null; father = null; partner = null; children = new ArrayList<FamilyMember>(); generation = 0; index = -1; } public void linkParent(FamilyMember parent) { if (parent.getGender().equals("Female")) { this.setMother(parent); } else { this.setFather(parent); } parent.addChild(this); } public void linkPartner(FamilyMember partner) { partner.setPartner(this); this.setPartner(partner); } public boolean hasParents() { if (this.getMother() == null && this.getFather() == null) { return false; } return true; } public FamilyMember getMother() { return mother; } public FamilyMember getFather() { return father; } public FamilyMember getPartner() { return partner; } public FamilyMember getChild(int index) { return children.get(index); } public int getGeneration() { return generation; } public int getIndex() { return index; } public ArrayList<FamilyMember> getChildren() { return children; } public void setMother(FamilyMember f) { mother = f; } public void setFather(FamilyMember f) { father = f; } public void setPartner(FamilyMember f) { partner = f; } public void addChild(FamilyMember f) { children.add(f); //add child if(children.size() > 1){ //sort in ascending order Collections.sort(children, new DateComparator()); } } public void addChildAt(FamilyMember f, int index) { children.set(index, f); } public void setGeneration(int g) { generation = g; } public void setIndex(int i){ index = i; } } package familytree; /** * * @author David */ public class Person{ private String fName; private String lName; private String gender; private int age; private String dob; public Person(String fName, String lName, String gender, String dob){ this.fName = fName; this.lName = lName; this.gender = gender; this.dob = dob; } public String getFullName(){ return (this.fName + " " + this.lName); } public String getFirstName(){ return (fName); } public String getLastName(){ return (lName); } public String getGender(){ return (gender); } public String getDob(){ return dob; } public int getAge(){ return age; } public void setFirstName(String fName){ this.fName = fName; } public void setLastName(String lName){ this.lName = lName; } public void setGender(String gender){ this.gender = gender; } public void setAge(int age){ this.age = age; } }

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  • C#/Resharper 5 structural search, detect and warn if any non-virtual public methods on classes with

    - by chillitom
    Hi All, I'm using LinFu's dynamic proxy to add some advice to some classes. The problem is that the proxied objects can only intercept virtual methods and will return the return type's default value for non-virtual methods. I can tell whether a class is proxied or not based whether the class or any of it's method has an interception attribute, e.g. [Transaction] Is it possible to write a ReSharper 5 structural search that would warn if any non-virtual public methods are defined on a class with an interception attribute. E.g. Ok public class InterceptedClass { [Transaction] public virtual void TransactionalMethod() { ... } public virtual void AnotherMethod() { ... } } Bad public class InterceptedClass { [Transaction] public virtual void TransactionalMethod() { ... } public void AnotherMethod() // non-virtual method will not be called by proxy { ... } } Many Thanks.

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  • PDAnet on Android IP on PC is not public IP. Where does the NAT take place, PDAnet or Verizon?

    - by lcbrevard
    When using PDAnet on a PC (Win7 ultimate) to USB tether a Motorola Droid on Verizon 3G the IP address of the PC appears to be public - 64.245.171.115 (64-245-171-115.pools.spcsdns.net) - but connections show as coming from another public IP - 97.14.69.212 (212-sub-97.14.69.myvzw.com). Someone is performing Network Address Translation - either PDAnet or within the Verizon 3G network. Can someone tell me who is doing the NAT? Is it PDAnet or is it at Verizon? Is there any possibility of setting up port forwarding, such that connections to the public IP 97.14.69.212 (212-sub-97.14.69.myvzw.com) are forward to the PC? We are testing a network protocol that requires either a true public IP or forwarding a range of ports from the public Internet to the system on which the software runs (actually Linux hosted by VMware Player or Workstation on a PC running Windows).

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  • Building a control-flow graph from an AST with a visitor pattern using Java

    - by omegatai
    Hi guys, I'm trying to figure out how to implement my LEParserCfgVisitor class as to build a control-flow graph from an Abstract-Syntax-Tree already generated with JavaCC. I know there are tools that already exist, but I'm trying to do it in preparation for my Compilers final. I know I need to have a data structure that keeps the graph in memory, and I want to be able to keep attributes like IN, OUT, GEN, KILL in each node as to be able to do a control-flow analysis later on. My main problem is that I haven't figured out how to connect the different blocks together, as to have the right edge between each blocks depending on their nature: branch, loops, etc. In other words, I haven't found an explicit algorithm that could help me build my visitor. Here is my empty Visitor. You can see it works on basic langage expressions, like if, while and basic operations (+,-,x,^,...) public class LEParserCfgVisitor implements LEParserVisitor { public Object visit(SimpleNode node, Object data) { return data; } public Object visit(ASTProgram node, Object data) { data = node.childrenAccept(this, data); return data; } public Object visit(ASTBlock node, Object data) { } public Object visit(ASTStmt node, Object data) { } public Object visit(ASTAssignStmt node, Object data) { } public Object visit(ASTIOStmt node, Object data) { } public Object visit(ASTIfStmt node, Object data) { } public Object visit(ASTWhileStmt node, Object data) { } public Object visit(ASTExpr node, Object data) { } public Object visit(ASTAddExpr node, Object data) { } public Object visit(ASTFactExpr node, Object data) { } public Object visit(ASTMultExpr node, Object data) { } public Object visit(ASTPowerExpr node, Object data) { } public Object visit(ASTUnaryExpr node, Object data) { } public Object visit(ASTBasicExpr node, Object data) { } public Object visit(ASTFctExpr node, Object data) { } public Object visit(ASTRealValue node, Object data) { } public Object visit(ASTIntValue node, Object data) { } public Object visit(ASTIdentifier node, Object data) { } } Can anyone give me a hand? Thanks!

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  • Unable to Calculate Position within Owner-Draw Text

    - by Jonathan Wood
    I'm trying to use Visual Studio 2012 to create a Windows Forms application that can place the caret at the current position within a owner-drawn string. However, I've been unable to find a way to accurately calculate that position. I've done this successfully before in C++. I've now tried numerous methods in C#. Originally, I tried using .NET classes to determine the correct position, but then I tried accessing the Windows API directly. In some cases, I came close, but after some time I still cannot place the caret accurately. I've created a small test program and posted key parts below. I've also posted the entire project here. The exact font used is not important to me; however, my application assumes a mono-spaced font. Any help is appreciated. Form1.cs This is my main form. public partial class Form1 : Form { private string TestString; private int AveCharWidth; private int Position; public Form1() { InitializeComponent(); TestString = "123456789012345678901234567890123456789012345678901234567890"; AveCharWidth = GetFontWidth(); Position = 0; } private void Form1_Load(object sender, EventArgs e) { Font = new Font(FontFamily.GenericMonospace, 12, FontStyle.Regular, GraphicsUnit.Pixel); } protected override void OnGotFocus(EventArgs e) { Windows.CreateCaret(Handle, (IntPtr)0, 2, (int)Font.Height); Windows.ShowCaret(Handle); UpdateCaretPosition(); base.OnGotFocus(e); } protected void UpdateCaretPosition() { Windows.SetCaretPos(Padding.Left + (Position * AveCharWidth), Padding.Top); } protected override void OnLostFocus(EventArgs e) { Windows.HideCaret(Handle); Windows.DestroyCaret(); base.OnLostFocus(e); } protected override void OnPaint(PaintEventArgs e) { e.Graphics.DrawString(TestString, Font, SystemBrushes.WindowText, new PointF(Padding.Left, Padding.Top)); } protected override bool IsInputKey(Keys keyData) { switch (keyData) { case Keys.Right: case Keys.Left: return true; } return base.IsInputKey(keyData); } protected override void OnKeyDown(KeyEventArgs e) { switch (e.KeyCode) { case Keys.Left: Position = Math.Max(Position - 1, 0); UpdateCaretPosition(); break; case Keys.Right: Position = Math.Min(Position + 1, TestString.Length); UpdateCaretPosition(); break; } base.OnKeyDown(e); } protected int GetFontWidth() { int AverageCharWidth = 0; using (var graphics = this.CreateGraphics()) { try { Windows.TEXTMETRIC tm; var hdc = graphics.GetHdc(); IntPtr hFont = this.Font.ToHfont(); IntPtr hOldFont = Windows.SelectObject(hdc, hFont); var a = Windows.GetTextMetrics(hdc, out tm); var b = Windows.SelectObject(hdc, hOldFont); var c = Windows.DeleteObject(hFont); AverageCharWidth = tm.tmAveCharWidth; } catch { } finally { graphics.ReleaseHdc(); } } return AverageCharWidth; } } Windows.cs Here are my Windows API declarations. public static class Windows { [Serializable, StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct TEXTMETRIC { public int tmHeight; public int tmAscent; public int tmDescent; public int tmInternalLeading; public int tmExternalLeading; public int tmAveCharWidth; public int tmMaxCharWidth; public int tmWeight; public int tmOverhang; public int tmDigitizedAspectX; public int tmDigitizedAspectY; public short tmFirstChar; public short tmLastChar; public short tmDefaultChar; public short tmBreakChar; public byte tmItalic; public byte tmUnderlined; public byte tmStruckOut; public byte tmPitchAndFamily; public byte tmCharSet; } [DllImport("user32.dll")] public static extern bool CreateCaret(IntPtr hWnd, IntPtr hBitmap, int nWidth, int nHeight); [DllImport("User32.dll")] public static extern bool SetCaretPos(int x, int y); [DllImport("User32.dll")] public static extern bool DestroyCaret(); [DllImport("User32.dll")] public static extern bool ShowCaret(IntPtr hWnd); [DllImport("User32.dll")] public static extern bool HideCaret(IntPtr hWnd); [DllImport("gdi32.dll", CharSet = CharSet.Auto)] public static extern bool GetTextMetrics(IntPtr hdc, out TEXTMETRIC lptm); [DllImport("gdi32.dll")] public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj); [DllImport("GDI32.dll")] public static extern bool DeleteObject(IntPtr hObject); }

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  • PDAnet on Android IP on PC is not public IP. Where does the NAT take place, PDAnet or Verizon?

    - by lcbrevard
    When using PDAnet on a PC (Win7 ultimate) to USB tether a Motorola Droid on Verizon 3G the IP address of the PC appears to be public - 64.245.171.115 (64-245-171-115.pools.spcsdns.net) - but connections show as coming from another public IP - 97.14.69.212 (212-sub-97.14.69.myvzw.com). Someone is performing Network Address Translation - either PDAnet or within the Verizon 3G network. Can someone tell me who is doing the NAT? Is it PDAnet or is it at Verizon? Is there any possibility of setting up port forwarding, such that connections to the public IP 97.14.69.212 (212-sub-97.14.69.myvzw.com) are forward to the PC? We are testing a network protocol that requires either a true public IP or forwarding a range of ports from the public Internet to the system on which the software runs (actually Linux hosted by VMware Player or Workstation on a PC running Windows).

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  • Performance issues in android game

    - by user1446632
    I am making an android game, but however, the game is functioning like it should, but i am experiencing some performance issues. I think it has something to do with the sound. Cause each time i touch the screen, it makes a sound. I am using the standard MediaPlayer. The method is onTouchEvent() and onPlaySound1(). Could you please help me with an alternate solution for playing the sound? Thank you so much in advance! It would be nice if you also came up with some suggestions on how i can improve my code. Take a look at my code here: package com.mycompany.mygame; import java.util.ArrayList; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.media.MediaPlayer; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.webkit.WebView; import android.widget.TextView; import android.widget.Toast; public class ExampleView extends SurfaceView implements SurfaceHolder.Callback { class ExampleThread extends Thread { private ArrayList<Parachuter> parachuters; private Bitmap parachuter; private Bitmap background; private Paint black; private boolean running; private SurfaceHolder mSurfaceHolder; private Context mContext; private Context mContext1; private Handler mHandler; private Handler mHandler1; private GameScreenActivity mActivity; private long frameRate; private boolean loading; public float x; public float y; public float x1; public float y1; public MediaPlayer mp1; public MediaPlayer mp2; public int parachuterIndexToResetAndDelete; public int canvasGetWidth; public int canvasGetWidth1; public int canvasGetHeight; public int livesLeftValue; public int levelValue = 1; public int levelValue1; public int parachutersDown; public int difficultySet; public boolean isSpecialAttackAvailible; public ExampleThread(SurfaceHolder sHolder, Context context, Handler handler) { mSurfaceHolder = sHolder; mHandler = handler; mHandler1 = handler; mContext = context; mActivity = (GameScreenActivity) context; parachuters = new ArrayList<Parachuter>(); parachuter = BitmapFactory.decodeResource(getResources(), R.drawable.parachuteman); black = new Paint(); black.setStyle(Paint.Style.FILL); black.setColor(Color.GRAY); background = BitmapFactory.decodeResource(getResources(), R.drawable.gamescreenbackground); running = true; // This equates to 26 frames per second. frameRate = (long) (1000 / 26); loading = true; mp1 = MediaPlayer.create(getContext(), R.raw.bombsound); } @Override public void run() { while (running) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas(); synchronized (mSurfaceHolder) { long start = System.currentTimeMillis(); doDraw(c); long diff = System.currentTimeMillis() - start; if (diff < frameRate) Thread.sleep(frameRate - diff); } } catch (InterruptedException e) { } finally { if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } protected void doDraw(Canvas canvas) { canvas.drawRect(0, 0, canvas.getWidth(), canvas.getHeight(), black); //Draw for (int i = 0; i < parachuters.size(); i++) { canvas.drawBitmap(parachuter, parachuters.get(i).getX(), parachuters.get(i).getY(), null); parachuters.get(i).tick(); } //Remove for (int i = 0; i < parachuters.size(); i++) { if (parachuters.get(i).getY() > canvas.getHeight()) { parachuters.remove(i); onPlaySound(); checkLivesLeftValue(); checkAmountOfParachuters(); } else if(parachuters.get(i).isTouched()) { parachuters.remove(i); } else{ //Do nothing } } } public void loadBackground(Canvas canvas) { //Load background canvas.drawBitmap(background, 0, 0, black); } public void checkAmountOfParachuters() { mHandler.post(new Runnable() { @Override public void run() { if(parachuters.isEmpty()) { levelValue = levelValue + 1; Toast.makeText(getContext(), "New level! " + levelValue, 15).show(); if (levelValue == 3) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); } else if (levelValue == 5) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); } else if (levelValue == 7) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); } else if (levelValue == 9) { //Draw 7 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); drawParachutersGroup1(); } else if (levelValue > 9) { //Draw 7 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); drawParachutersGroup1(); } else { //Draw normal 3 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); } } else { //Do nothing } } }); } private void checkLivesLeftValue() { mHandler.post(new Runnable() { @Override public void run() { Log.d("checkLivesLeftValue", "lives = " + livesLeftValue); // TODO Auto-generated method stub if (livesLeftValue == 3) { //Message to display: "You lost! Log.d("checkLivesLeftValue", "calling onMethod now"); parachuters.removeAll(parachuters); onMethod(); } else if (livesLeftValue == 2) { Toast.makeText(getContext(), "Lives left=1", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } else if (livesLeftValue == 1) { Toast.makeText(getContext(), "Lives left=2", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } else { //Set livesLeftValueText 3 Toast.makeText(getContext(), "Lives left=3", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } } }); } public void onMethod() { mHandler.post(new Runnable() { @Override public void run() { try { Toast.makeText(getContext(), "You lost!", 15).show(); livesLeftValue = 0; //Tell the user that he lost: android.content.Context ctx = mContext; Intent i = new Intent(ctx, playerLostMessageActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.putExtra("KEY","You got to level " + levelValue + " And you shot down " + parachutersDown + " parachuters"); i.putExtra("levelValue", levelValue); ctx.startActivity(i); System.exit(0); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); //Exit activity and start playerLostMessageActivity Toast.makeText(getContext(), "You lost!", 15).show(); livesLeftValue = 0; //Tell the user that he lost: android.content.Context ctx = mContext; Intent i = new Intent(ctx, playerLostMessageActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.putExtra("KEY","You got to level " + levelValue + " And you shot down " + parachutersDown + " parachuters"); i.putExtra("levelValue", levelValue); System.exit(0); ctx.startActivity(i); System.exit(0); } } }); } public void onPlaySound() { try { mp1.start(); } catch (Exception e) { e.printStackTrace(); mp1.release(); } } public void onDestroy() { try { parachuters.removeAll(parachuters); mp1.stop(); mp1.release(); } catch (Exception e) { e.printStackTrace(); } } public void onPlaySound1() { try { mp2 = MediaPlayer.create(getContext(), R.raw.airriflesoundeffect); mp2.start(); } catch (Exception e) { e.printStackTrace(); mp2.release(); } } public boolean onTouchEvent(MotionEvent event) { if (event.getAction() != MotionEvent.ACTION_DOWN) releaseMediaPlayer(); x1 = event.getX(); y1 = event.getY(); checkAmountOfParachuters(); removeParachuter(); return false; } public void releaseMediaPlayer() { try { mp1.release(); } catch (Exception e) { e.printStackTrace(); } } public void removeParachuter() { try { for (Parachuter p: parachuters) { if (x1 > p.getX() && x1 < p.getX() + parachuter.getWidth() && y1 > p.getY() && y1 < p.getY() + parachuter.getHeight()) { p.setTouched(true); onPlaySound1(); parachutersDown = parachutersDown + 1; p.setTouched(false); } } } catch (Exception e) { e.printStackTrace(); } } public void initiateDrawParachuters() { drawParachutersGroup1(); } public void drawParachutersGroup1() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 75; y = 77; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 14; y = 28; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 250; y = 94; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 275; y = 80; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 280; y = 163; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 125; y = 118; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 126; y = 247; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 123; y = 77; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup2() { // TODO Auto-generated method stub //Parachuter group nr. 2 //Parachuter nr. 5 x = 153; y = 166; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 133; y = 123; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 170; y = 213; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 190; y = 121; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup3() { // TODO Auto-generated method stub //Parachuter group nr. 3 //Parachuter nr. 2 x = 267; y = 115; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 255; y = 183; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 170; y = 280; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 116; y = 80; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 67; y = 112; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 260; y = 89; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 260; y = 113; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 178; y = 25; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup4() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 75; y = 166; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 118; y = 94; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 38; y = 55; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 57; y = 18; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 67; y = 119; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 217; y = 113; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 245; y = 234; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 239; y = 44; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup5() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 59; y = 120; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 210; y = 169; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 199; y = 138; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 22; y = 307; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 195; y = 22; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 157; y = 132; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 150; y = 183; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 130; y = 20; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup6() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 10; y = 10; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 20; y = 20; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 30; y = 30; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 60; y = 60; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 90; y = 90; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 120; y = 120; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 150; y = 150; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 180; y = 180; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachuters() { Parachuter p = new Parachuter(x, y); parachuters.add(p); Toast.makeText(getContext(), "x=" + x + " y=" + y, 15).show(); } public void setRunning(boolean bRun) { running = bRun; } public boolean getRunning() { return running; } } /** Handle to the application context, used to e.g. fetch Drawables. */ private Context mContext; /** Pointer to the text view to display "Paused.." etc. */ private TextView mStatusText; /** The thread that actually draws the animation */ private ExampleThread eThread; public ExampleView(Context context) { super(context); // register our interest in hearing about changes to our surface SurfaceHolder holder = getHolder(); holder.addCallback(this); // create thread only; it's started in surfaceCreated() eThread = new ExampleThread(holder, context, new Handler() { @Override public void handleMessage(Message m) { // mStatusText.setVisibility(m.getData().getInt("viz")); // mStatusText.setText(m.getData().getString("text")); } }); setFocusable(true); } @Override public boolean onTouchEvent(MotionEvent event) { return eThread.onTouchEvent(event); } public ExampleThread getThread() { return eThread; } @Override public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) { // TODO Auto-generated method stub } public void surfaceCreated(SurfaceHolder holder) { if (eThread.getState() == Thread.State.TERMINATED) { eThread = new ExampleThread(getHolder(), getContext(), getHandler()); eThread.start(); } else { eThread.start(); } } @Override public void surfaceDestroyed(SurfaceHolder holder) { boolean retry = true; eThread.setRunning(false); while (retry) { try { eThread.join(); retry = false; } catch (InterruptedException e) { } } } }

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  • Entity Framework does not map 2 columns from a SqlQuery calling a stored procedure

    - by user1783530
    I'm using Code First and am trying to call a stored procedure and have it map to one of my classes. I created a stored procedure, BOMComponentChild, that returns details of a Component with information of its hierarchy in PartsPath and MyPath. I have a class for the output of this stored procedure. I'm having an issue where everything except the two columns, PartsPath and MyPath, are being mapped correctly with these two properties ending up as Nothing. I searched around and from my understanding the mapping bypasses any Entity Framework name mapping and uses column name to property name. The names are the same and I'm not sure why it is only these two columns. The last part of the stored procedure is: SELECT t.ParentID ,t.ComponentID ,c.PartNumber ,t.PartsPath ,t.MyPath ,t.Layer ,c.[Description] ,loc.LocationID ,loc.LocationName ,CASE WHEN sup.SupplierID IS NULL THEN 1 ELSE sup.SupplierID END AS SupplierID ,CASE WHEN sup.SupplierName IS NULL THEN 'Scinomix' ELSE sup.SupplierName END AS SupplierName ,c.Active ,c.QA ,c.IsAssembly ,c.IsPurchasable ,c.IsMachined ,t.QtyRequired ,t.TotalQty FROM BuildProducts t INNER JOIN [dbo].[BOMComponent] c ON c.ComponentID = t.ComponentID LEFT JOIN [dbo].[BOMSupplier] bsup ON bsup.ComponentID = t.ComponentID AND bsup.IsDefault = 1 LEFT JOIN [dbo].[LookupSupplier] sup ON sup.SupplierID = bsup.SupplierID LEFT JOIN [dbo].[LookupLocation] loc ON loc.LocationID = c.LocationID WHERE (@IsAssembly IS NULL OR IsAssembly = @IsAssembly) ORDER BY t.MyPath and the class it maps to is: Public Class BOMComponentChild Public Property ParentID As Nullable(Of Integer) Public Property ComponentID As Integer Public Property PartNumber As String Public Property MyPath As String Public Property PartsPath As String Public Property Layer As Integer Public Property Description As String Public Property LocationID As Integer Public Property LocationName As String Public Property SupplierID As Integer Public Property SupplierName As String Public Property Active As Boolean Public Property QA As Boolean Public Property IsAssembly As Boolean Public Property IsPurchasable As Boolean Public Property IsMachined As Boolean Public Property QtyRequired As Integer Public Property TotalQty As Integer Public Property Children As IDictionary(Of String, BOMComponentChild) = New Dictionary(Of String, BOMComponentChild) End Class I am trying to call it like this: Me.Database.SqlQuery(Of BOMComponentChild)("EXEC [BOMComponentChild] @ComponentID, @PathPrefix, @IsAssembly", params).ToList() When I run the stored procedure in management studio, the columns are correct and not null. I just can't figure out why these won't map as they are the important information in the stored procedure. The types for PartsPath and MyPath are varchar(50).

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  • Custom Content Pipeline with Automatic Serialization Load Error

    - by Direweasel
    I'm running into this error: Error loading "desert". Cannot find type TiledLib.MapContent, TiledLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null. at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.InstantiateTypeReader(String readerTypeName, ContentReader contentReader, ContentTypeReader& reader) at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.GetTypeReader(String readerTypeName, ContentReader contentReader, List1& newTypeReaders) at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.ReadTypeManifest(Int32 typeCount, ContentReader contentReader) at Microsoft.Xna.Framework.Content.ContentReader.ReadHeader() at Microsoft.Xna.Framework.Content.ContentReader.ReadAsset[T]() at Microsoft.Xna.Framework.Content.ContentManager.ReadAsset[T](String assetName, Action1 recordDisposableObject) at Microsoft.Xna.Framework.Content.ContentManager.Load[T](String assetName) at TiledTest.Game1.LoadContent() in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Game1.cs:line 51 at Microsoft.Xna.Framework.Game.Initialize() at TiledTest.Game1.Initialize() in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Game1.cs:line 39 at Microsoft.Xna.Framework.Game.RunGame(Boolean useBlockingRun) at Microsoft.Xna.Framework.Game.Run() at TiledTest.Program.Main(String[] args) in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Program.cs:line 15 When trying to run the game. This is a basic demo to try and utilize a separate project library called TiledLib. I have four projects overall: TiledLib (C# Class Library) TiledTest (Windows Game) TiledTestContent (Content) TMX CP Ext (Content Pipeline Extension Library) TiledLib contains MapContent which is throwing the error, however I believe this may just be a generic error with a deeper root problem. EMX CP Ext contains one file: MapProcessor.cs using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Content.Pipeline; using Microsoft.Xna.Framework.Content.Pipeline.Graphics; using Microsoft.Xna.Framework.Content.Pipeline.Processors; using Microsoft.Xna.Framework.Content; using TiledLib; namespace TMX_CP_Ext { // Each tile has a texture, source rect, and sprite effects. [ContentSerializerRuntimeType("TiledTest.Tile, TiledTest")] public class DemoMapTileContent { public ExternalReference<Texture2DContent> Texture; public Rectangle SourceRectangle; public SpriteEffects SpriteEffects; } // For each layer, we store the size of the layer and the tiles. [ContentSerializerRuntimeType("TiledTest.Layer, TiledTest")] public class DemoMapLayerContent { public int Width; public int Height; public DemoMapTileContent[] Tiles; } // For the map itself, we just store the size, tile size, and a list of layers. [ContentSerializerRuntimeType("TiledTest.Map, TiledTest")] public class DemoMapContent { public int TileWidth; public int TileHeight; public List<DemoMapLayerContent> Layers = new List<DemoMapLayerContent>(); } [ContentProcessor(DisplayName = "TMX Processor - TiledLib")] public class MapProcessor : ContentProcessor<MapContent, DemoMapContent> { public override DemoMapContent Process(MapContent input, ContentProcessorContext context) { // build the textures TiledHelpers.BuildTileSetTextures(input, context); // generate source rectangles TiledHelpers.GenerateTileSourceRectangles(input); // now build our output, first by just copying over some data DemoMapContent output = new DemoMapContent { TileWidth = input.TileWidth, TileHeight = input.TileHeight }; // iterate all the layers of the input foreach (LayerContent layer in input.Layers) { // we only care about tile layers in our demo TileLayerContent tlc = layer as TileLayerContent; if (tlc != null) { // create the new layer DemoMapLayerContent outLayer = new DemoMapLayerContent { Width = tlc.Width, Height = tlc.Height, }; // we need to build up our tile list now outLayer.Tiles = new DemoMapTileContent[tlc.Data.Length]; for (int i = 0; i < tlc.Data.Length; i++) { // get the ID of the tile uint tileID = tlc.Data[i]; // use that to get the actual index as well as the SpriteEffects int tileIndex; SpriteEffects spriteEffects; TiledHelpers.DecodeTileID(tileID, out tileIndex, out spriteEffects); // figure out which tile set has this tile index in it and grab // the texture reference and source rectangle. ExternalReference<Texture2DContent> textureContent = null; Rectangle sourceRect = new Rectangle(); // iterate all the tile sets foreach (var tileSet in input.TileSets) { // if our tile index is in this set if (tileIndex - tileSet.FirstId < tileSet.Tiles.Count) { // store the texture content and source rectangle textureContent = tileSet.Texture; sourceRect = tileSet.Tiles[(int)(tileIndex - tileSet.FirstId)].Source; // and break out of the foreach loop break; } } // now insert the tile into our output outLayer.Tiles[i] = new DemoMapTileContent { Texture = textureContent, SourceRectangle = sourceRect, SpriteEffects = spriteEffects }; } // add the layer to our output output.Layers.Add(outLayer); } } // return the output object. because we have ContentSerializerRuntimeType attributes on our // objects, we don't need a ContentTypeWriter and can just use the automatic serialization. return output; } } } TiledLib contains a large amount of files including MapContent.cs using System; using System.Collections.Generic; using System.Globalization; using System.Xml; using Microsoft.Xna.Framework.Content.Pipeline; namespace TiledLib { public enum Orientation : byte { Orthogonal, Isometric, } public class MapContent { public string Filename; public string Directory; public string Version = string.Empty; public Orientation Orientation; public int Width; public int Height; public int TileWidth; public int TileHeight; public PropertyCollection Properties = new PropertyCollection(); public List<TileSetContent> TileSets = new List<TileSetContent>(); public List<LayerContent> Layers = new List<LayerContent>(); public MapContent(XmlDocument document, ContentImporterContext context) { XmlNode mapNode = document["map"]; Version = mapNode.Attributes["version"].Value; Orientation = (Orientation)Enum.Parse(typeof(Orientation), mapNode.Attributes["orientation"].Value, true); Width = int.Parse(mapNode.Attributes["width"].Value, CultureInfo.InvariantCulture); Height = int.Parse(mapNode.Attributes["height"].Value, CultureInfo.InvariantCulture); TileWidth = int.Parse(mapNode.Attributes["tilewidth"].Value, CultureInfo.InvariantCulture); TileHeight = int.Parse(mapNode.Attributes["tileheight"].Value, CultureInfo.InvariantCulture); XmlNode propertiesNode = document.SelectSingleNode("map/properties"); if (propertiesNode != null) { Properties = new PropertyCollection(propertiesNode, context); } foreach (XmlNode tileSet in document.SelectNodes("map/tileset")) { if (tileSet.Attributes["source"] != null) { TileSets.Add(new ExternalTileSetContent(tileSet, context)); } else { TileSets.Add(new TileSetContent(tileSet, context)); } } foreach (XmlNode layerNode in document.SelectNodes("map/layer|map/objectgroup")) { LayerContent layerContent; if (layerNode.Name == "layer") { layerContent = new TileLayerContent(layerNode, context); } else if (layerNode.Name == "objectgroup") { layerContent = new MapObjectLayerContent(layerNode, context); } else { throw new Exception("Unknown layer name: " + layerNode.Name); } // Layer names need to be unique for our lookup system, but Tiled // doesn't require unique names. string layerName = layerContent.Name; int duplicateCount = 2; // if a layer already has the same name... if (Layers.Find(l => l.Name == layerName) != null) { // figure out a layer name that does work do { layerName = string.Format("{0}{1}", layerContent.Name, duplicateCount); duplicateCount++; } while (Layers.Find(l => l.Name == layerName) != null); // log a warning for the user to see context.Logger.LogWarning(string.Empty, new ContentIdentity(), "Renaming layer \"{1}\" to \"{2}\" to make a unique name.", layerContent.Type, layerContent.Name, layerName); // save that name layerContent.Name = layerName; } Layers.Add(layerContent); } } } } I'm lost as to why this is failing. Thoughts? -- EDIT -- After playing with it a bit, I would think it has something to do with referencing the projects. I'm already referencing the TiledLib within my main windows project (TiledTest). However, this doesn't seem to make a difference. I can place the dll generated from the TiledLib project into the debug folder of TiledTest, and this causes it to generate a different error: Error loading "desert". Cannot find ContentTypeReader for Microsoft.Xna.Framework.Content.Pipeline.ExternalReference`1[Microsoft.Xna.Framework.Content.Pipeline.Graphics.Texture2DContent]. at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.GetTypeReader(Type targetType, ContentReader contentReader) at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.GetTypeReader(Type targetType) at Microsoft.Xna.Framework.Content.ReflectiveReaderMemberHelper..ctor(ContentTypeReaderManager manager, FieldInfo fieldInfo, PropertyInfo propertyInfo, Type memberType, Boolean canWrite) at Microsoft.Xna.Framework.Content.ReflectiveReaderMemberHelper.TryCreate(ContentTypeReaderManager manager, Type declaringType, FieldInfo fieldInfo) at Microsoft.Xna.Framework.Content.ReflectiveReader1.Initialize(ContentTypeReaderManager manager) at Microsoft.Xna.Framework.Content.ContentTypeReaderManager.ReadTypeManifest(Int32 typeCount, ContentReader contentReader) at Microsoft.Xna.Framework.Content.ContentReader.ReadHeader() at Microsoft.Xna.Framework.Content.ContentReader.ReadAsset[T]() at Microsoft.Xna.Framework.Content.ContentManager.ReadAsset[T](String assetName, Action1 recordDisposableObject) at Microsoft.Xna.Framework.Content.ContentManager.Load[T](String assetName) at TiledTest.Game1.LoadContent() in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Game1.cs:line 51 at Microsoft.Xna.Framework.Game.Initialize() at TiledTest.Game1.Initialize() in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Game1.cs:line 39 at Microsoft.Xna.Framework.Game.RunGame(Boolean useBlockingRun) at Microsoft.Xna.Framework.Game.Run() at TiledTest.Program.Main(String[] args) in C:\My Documents\Dropbox\Visual Studio Projects\TiledTest\TiledTest\TiledTest\Program.cs:line 15 This is all incredibly frustrating as the demo doesn't appear to have any special linking properties. The TiledLib I am utilizing is from Nick Gravelyn, and can be found here: https://bitbucket.org/nickgravelyn/tiledlib. The demo it comes with works fine, and yet in recreating I always run into this error.

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  • Why do my LWJGL fonts have dots and lines around them?

    - by Jordan
    When we render fonts there are weird dots and lines around the text. I have no idea why this would happen. Here is an image of what it looks like: Our font class looks like this: package me.NJ.ComputerTycoon.Font; import me.NJ.ComputerTycoon.BaseObjects.UDim2; import org.lwjgl.opengl.Display; import org.newdawn.slick.Color; import org.newdawn.slick.TrueTypeFont; public class Font { public TrueTypeFont font; private int fontSize = 18; private String fontName = "Calibri"; private int fontStyle = java.awt.Font.BOLD; public Font(String fontName, int fontStyle, int fontSize) { font = new TrueTypeFont(new java.awt.Font(fontName, fontStyle, fontSize), true); //font. } public Font(int fontStyle, int fontSize) { font = new TrueTypeFont(new java.awt.Font(fontName, fontStyle, fontSize), true); } public Font(int fontSize) { font = new TrueTypeFont(new java.awt.Font(fontName, fontStyle, fontSize), true); } public Font() { font = new TrueTypeFont(new java.awt.Font(fontName, fontStyle, fontSize), true); } public void drawString(int x, int y, String s, Color color){ this.font.drawString(x, y, s, color); } public void drawString(int x, int y, String s){ this.font.drawString(x, y, s); } public void drawString(float x, float y, String s, Color color){ this.font.drawString(x, y, s, color); } public void drawString(float x, float y, String s){ this.font.drawString(x, y, s); } public void drawString(UDim2 udim, String s){ this.font.drawString((Display.getWidth() * udim.getX().getScale()) + udim.getX().getOffset(), (Display.getHeight() * udim.getY().getScale()) + udim.getY().getOffset(), s); } public String getFontName(){ return this.fontName; } public int getFontSize(){ return this.fontSize; } public TrueTypeFont getFont(){ return this.font; } } What could be causing this?

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  • This code is of chess game. What is represented by 'DISTANCE' in code? [closed]

    - by rajeshverma423
    package chess; public class Evaluate { public static final int PIECE_KING = 0; public static final int PIECE_QUEEN = 1; public static final int PIECE_ROOK = 2; public static final int PIECE_BISHOP = 3; public static final int PIECE_KNIGHT = 4; public static final int PIECE_PAWN = 5; public static final int FULL_BIT_RANK = 4080; public static final int LAZY_MARGIN = 100; public static final int ISOLATED_PENALTY = 10; public static final int DOUBLE_PENALTY = 4; public static final int[] PIECE_VALUE = { 0, 9, 5, 3, 3, 1 }; public static final int[] PASS_PAWN = { 0, 35, 30, 20, 10, 5 }; public static final byte[] DISTANCE = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 5, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 3, 4, 5, 6, 7, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 3, 2, 3, 4, 5, 6, 7, 0, 0, 0, 0, 7, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6, 7, 0, 0, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 0, 0, 7, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6, 7, 0, 0, 0, 0, 7, 6, 5, 4, 3, 2, 3, 4, 5, 6, 7, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 3, 4, 5, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 5, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7 };

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  • Box2D how to implement a camera?

    - by Romeo
    By now i have this Camera class. package GameObjects; import main.Main; import org.jbox2d.common.Vec2; public class Camera { public int x; public int y; public int sx; public int sy; public static final float PIXEL_TO_METER = 50f; private float yFlip = -1.0f; public Camera() { x = 0; y = 0; sx = x + Main.APPWIDTH; sy = y + Main.APPHEIGHT; } public Camera(int x, int y) { this.x = x; this.y = y; sx = x + Main.APPWIDTH; sy = y + Main.APPHEIGHT; } public void update() { sx = x + Main.APPWIDTH; sy = y + Main.APPHEIGHT; } public void moveCam(int mx, int my) { if(mx >= 0 && mx <= 80) { this.x -= 2; } else if(mx <= Main.APPWIDTH && mx >= Main.APPWIDTH - 80) { this.x += 2; } if(my >= 0 && my <= 80) { this.y += 2; } else if(my <= Main.APPHEIGHT && my >= Main.APPHEIGHT - 80) { this.y -= 2; } this.update(); } public float meterToPixel(float meter) { return meter * PIXEL_TO_METER; } public float pixelToMeter(float pixel) { return pixel / PIXEL_TO_METER; } public Vec2 screenToWorld(Vec2 screenV) { return new Vec2(screenV.x + this.x, yFlip * screenV.y + this.y); } public Vec2 worldToScreen(Vec2 worldV) { return new Vec2(worldV.x - this.x, yFlip * worldV.y - this.y); } } I need to know how to modify the screenToWorld and worldToScreen functions to include the PIXEL_TO_METER scaling.

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  • Confused about implementing Single Responsibility Principle

    - by HichemSeeSharp
    Please bear with me if the question looks not well structured. To put you in the context of my issue: I am building an application that invoices vehicles stay duration in a parking. In addition to the stay service there are some other services. Each service has its own calculation logic. Here is an illustration (please correct me if the design is wrong): public abstract class Service { public int Id { get; set; } public bool IsActivated { get; set; } public string Name { get; set } public decimal Price { get; set; } } public class VehicleService : Service { //MTM : many to many public virtual ICollection<MTMVehicleService> Vehicles { get; set; } } public class StayService : VehicleService { } public class Vehicle { public int Id { get; set; } public string ChassisNumber { get; set; } public DateTime? EntryDate { get; set; } public DateTime? DeliveryDate { get; set; } //... public virtual ICollection<MTMVehicleService> Services{ get; set; } } Now, I am focusing on the stay service as an example: I would like to know at invoicing time which class(es) would be responsible for generating the invoice item for the service and for each vehicle? This should calculate the duration cost knowing that the duration could be invoiced partially so the like is as follows: not yet invoiced stay days * stay price per day. At this moment I have InvoiceItemsGenerator do everything but I am aware that there is a better design.

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  • Is there a name for the Builder Pattern where the Builder is implemented via interfaces so certain parameters are required?

    - by Zipper
    So we implemented the builder pattern for most of our domain to help in understandability of what actually being passed to a constructor, and for the normal advantages that a builder gives. The one twist was that we exposed the builder through interfaces so we could chain required functions and unrequired functions to make sure that the correct parameters were passed. I was curious if there was an existing pattern like this. Example below: public class Foo { private int someThing; private int someThing2; private DateTime someThing3; private Foo(Builder builder) { this.someThing = builder.someThing; this.someThing2 = builder.someThing2; this.someThing3 = builder.someThing3; } public static RequiredSomething getBuilder() { return new Builder(); } public interface RequiredSomething { public RequiredDateTime withSomething (int value); } public interface RequiredDateTime { public OptionalParamters withDateTime (DateTime value); } public interface OptionalParamters { public OptionalParamters withSeomthing2 (int value); public Foo Build ();} public static class Builder implements RequiredSomething, RequiredDateTime, OptionalParamters { private int someThing; private int someThing2; private DateTime someThing3; public RequiredDateTime withSomething (int value) {someThing = value; return this;} public OptionalParamters withDateTime (int value) {someThing = value; return this;} public OptionalParamters withSeomthing2 (int value) {someThing = value; return this;} public Foo build(){return new Foo(this);} } } Example of how it's called: Foo foo = Foo.getBuilder().withSomething(1).withDateTime(DateTime.now()).build(); Foo foo2 = Foo.getBuilder().withSomething(1).withDateTime(DateTime.now()).withSomething2(3).build();

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  • Which order to define getters and setters in? [closed]

    - by N.N.
    Is there a best practice for the order to define getters and setters in? There seems to be two practices: getter/setter pairs first getters, then setters (or the other way around) To illuminate the difference here is a Java example of getter/setter pairs: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public void setVar1(int var1) { this.var1 = var1; } public int getVar2() { return var2; } public void setVar2(int var2) { this.var2 = var2; } public int getVar3() { return var3; } public void setVar3(int var3) { this.var3 = var3; } } And here is a Java example of first getters, then setters: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public int getVar2() { return var2; } public int getVar3() { return var3; } public void setVar1(int var1) { this.var1 = var1; } public void setVar2(int var2) { this.var2 = var2; } public void setVar3(int var3) { this.var3 = var3; } } I think the latter type of ordering is clearer both in code and in class diagrams but I do not know if that is enough to rule out the other type of ordering.

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  • Maintaining shared service in ASP.NET MVC Application

    - by kazimanzurrashid
    Depending on the application sometimes we have to maintain some shared service throughout our application. Let’s say you are developing a multi-blog supported blog engine where both the controller and view must know the currently visiting blog, it’s setting , user information and url generation service. In this post, I will show you how you can handle this kind of case in most convenient way. First, let see the most basic way, we can create our PostController in the following way: public class PostController : Controller { public PostController(dependencies...) { } public ActionResult Index(string blogName, int? page) { BlogInfo blog = blogSerivce.FindByName(blogName); if (blog == null) { return new NotFoundResult(); } IEnumerable<PostInfo> posts = postService.FindPublished(blog.Id, PagingCalculator.StartIndex(page, blog.PostPerPage), blog.PostPerPage); int count = postService.GetPublishedCount(blog.Id); UserInfo user = null; if (HttpContext.User.Identity.IsAuthenticated) { user = userService.FindByName(HttpContext.User.Identity.Name); } return View(new IndexViewModel(urlResolver, user, blog, posts, count, page)); } public ActionResult Archive(string blogName, int? page, ArchiveDate archiveDate) { BlogInfo blog = blogSerivce.FindByName(blogName); if (blog == null) { return new NotFoundResult(); } IEnumerable<PostInfo> posts = postService.FindArchived(blog.Id, archiveDate, PagingCalculator.StartIndex(page, blog.PostPerPage), blog.PostPerPage); int count = postService.GetArchivedCount(blog.Id, archiveDate); UserInfo user = null; if (HttpContext.User.Identity.IsAuthenticated) { user = userService.FindByName(HttpContext.User.Identity.Name); } return View(new ArchiveViewModel(urlResolver, user, blog, posts, count, page, achiveDate)); } public ActionResult Tag(string blogName, string tagSlug, int? page) { BlogInfo blog = blogSerivce.FindByName(blogName); if (blog == null) { return new NotFoundResult(); } TagInfo tag = tagService.FindBySlug(blog.Id, tagSlug); if (tag == null) { return new NotFoundResult(); } IEnumerable<PostInfo> posts = postService.FindPublishedByTag(blog.Id, tag.Id, PagingCalculator.StartIndex(page, blog.PostPerPage), blog.PostPerPage); int count = postService.GetPublishedCountByTag(tag.Id); UserInfo user = null; if (HttpContext.User.Identity.IsAuthenticated) { user = userService.FindByName(HttpContext.User.Identity.Name); } return View(new TagViewModel(urlResolver, user, blog, posts, count, page, tag)); } } As you can see the above code heavily depends upon the current blog and the blog retrieval code is duplicated in all of the action methods, once the blog is retrieved the same blog is passed in the view model. Other than the blog the view also needs the current user and url resolver to render it properly. One way to remove the duplicate blog retrieval code is to create a custom model binder which converts the blog from a blog name and use the blog a parameter in the action methods instead of the string blog name, but it only helps the first half in the above scenario, the action methods still have to pass the blog, user and url resolver etc in the view model. Now lets try to improve the the above code, first lets create a new class which would contain the shared services, lets name it as BlogContext: public class BlogContext { public BlogInfo Blog { get; set; } public UserInfo User { get; set; } public IUrlResolver UrlResolver { get; set; } } Next, we will create an interface, IContextAwareService: public interface IContextAwareService { BlogContext Context { get; set; } } The idea is, whoever needs these shared services needs to implement this interface, in our case both the controller and the view model, now we will create an action filter which will be responsible for populating the context: public class PopulateBlogContextAttribute : FilterAttribute, IActionFilter { private static string blogNameRouteParameter = "blogName"; private readonly IBlogService blogService; private readonly IUserService userService; private readonly BlogContext context; public PopulateBlogContextAttribute(IBlogService blogService, IUserService userService, IUrlResolver urlResolver) { Invariant.IsNotNull(blogService, "blogService"); Invariant.IsNotNull(userService, "userService"); Invariant.IsNotNull(urlResolver, "urlResolver"); this.blogService = blogService; this.userService = userService; context = new BlogContext { UrlResolver = urlResolver }; } public static string BlogNameRouteParameter { [DebuggerStepThrough] get { return blogNameRouteParameter; } [DebuggerStepThrough] set { blogNameRouteParameter = value; } } public void OnActionExecuting(ActionExecutingContext filterContext) { string blogName = (string) filterContext.Controller.ValueProvider.GetValue(BlogNameRouteParameter).ConvertTo(typeof(string), Culture.Current); if (!string.IsNullOrWhiteSpace(blogName)) { context.Blog = blogService.FindByName(blogName); } if (context.Blog == null) { filterContext.Result = new NotFoundResult(); return; } if (filterContext.HttpContext.User.Identity.IsAuthenticated) { context.User = userService.FindByName(filterContext.HttpContext.User.Identity.Name); } IContextAwareService controller = filterContext.Controller as IContextAwareService; if (controller != null) { controller.Context = context; } } public void OnActionExecuted(ActionExecutedContext filterContext) { Invariant.IsNotNull(filterContext, "filterContext"); if ((filterContext.Exception == null) || filterContext.ExceptionHandled) { IContextAwareService model = filterContext.Controller.ViewData.Model as IContextAwareService; if (model != null) { model.Context = context; } } } } As you can see we are populating the context in the OnActionExecuting, which executes just before the controllers action methods executes, so by the time our action methods executes the context is already populated, next we are are assigning the same context in the view model in OnActionExecuted method which executes just after we set the  model and return the view in our action methods. Now, lets change the view models so that it implements this interface: public class IndexViewModel : IContextAwareService { // More Codes } public class ArchiveViewModel : IContextAwareService { // More Codes } public class TagViewModel : IContextAwareService { // More Codes } and the controller: public class PostController : Controller, IContextAwareService { public PostController(dependencies...) { } public BlogContext Context { get; set; } public ActionResult Index(int? page) { IEnumerable<PostInfo> posts = postService.FindPublished(Context.Blog.Id, PagingCalculator.StartIndex(page, Context.Blog.PostPerPage), Context.Blog.PostPerPage); int count = postService.GetPublishedCount(Context.Blog.Id); return View(new IndexViewModel(posts, count, page)); } public ActionResult Archive(int? page, ArchiveDate archiveDate) { IEnumerable<PostInfo> posts = postService.FindArchived(Context.Blog.Id, archiveDate, PagingCalculator.StartIndex(page, Context.Blog.PostPerPage), Context.Blog.PostPerPage); int count = postService.GetArchivedCount(Context.Blog.Id, archiveDate); return View(new ArchiveViewModel(posts, count, page, achiveDate)); } public ActionResult Tag(string blogName, string tagSlug, int? page) { TagInfo tag = tagService.FindBySlug(Context.Blog.Id, tagSlug); if (tag == null) { return new NotFoundResult(); } IEnumerable<PostInfo> posts = postService.FindPublishedByTag(Context.Blog.Id, tag.Id, PagingCalculator.StartIndex(page, Context.Blog.PostPerPage), Context.Blog.PostPerPage); int count = postService.GetPublishedCountByTag(tag.Id); return View(new TagViewModel(posts, count, page, tag)); } } Now, the last thing where we have to glue everything, I will be using the AspNetMvcExtensibility to register the action filter (as there is no better way to inject the dependencies in action filters). public class RegisterFilters : RegisterFiltersBase { private static readonly Type controllerType = typeof(Controller); private static readonly Type contextAwareType = typeof(IContextAwareService); protected override void Register(IFilterRegistry registry) { TypeCatalog controllers = new TypeCatalogBuilder() .Add(GetType().Assembly) .Include(type => controllerType.IsAssignableFrom(type) && contextAwareType.IsAssignableFrom(type)); registry.Register<PopulateBlogContextAttribute>(controllers); } } Thoughts and Comments?

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  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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  • readonly keyword

    - by nmarun
    This is something new that I learned about the readonly keyword. Have a look at the following class: 1: public class MyClass 2: { 3: public string Name { get; set; } 4: public int Age { get; set; } 5:  6: private readonly double Delta; 7:  8: public MyClass() 9: { 10: Initializer(); 11: } 12:  13: public MyClass(string name = "", int age = 0) 14: { 15: Name = name; 16: Age = age; 17: Initializer(); 18: } 19:  20: private void Initializer() 21: { 22: Delta = 0.2; 23: } 24: } I have a couple of public properties and a private readonly member. There are two constructors – one that doesn’t take any parameters and the other takes two parameters to initialize the public properties. I’m also calling the Initializer method in both constructors to initialize the readonly member. Now when I build this, the code breaks and the Error window says: “A readonly field cannot be assigned to (except in a constructor or a variable initializer)” Two things after I read this message: It’s such a negative statement. I’d prefer something like: “A readonly field can be assigned to (or initialized) only in a constructor or through a variable initializer” But in my defense, I AM assigning it in a constructor (only indirectly). All I’m doing is creating a method that does it and calling it in a constructor. Turns out, .net was not ‘frameworked’ this way. We need to have the member initialized directly in the constructor. If you have multiple constructors, you can just use the ‘this’ keyword on all except the default constructors to call the default constructor. This default constructor can then initialize your readonly members. This will ensure you’re not repeating the code in multiple places. A snippet of what I’m talking can be seen below: 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha; 10: private readonly int Beta; 11: private readonly double Delta; 12: private readonly double Gamma; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: } 26: } See the syntax in line 22 and you’ll know what I’m talking about. So the default constructor gets called before the one in line 22. These are known as constructor initializers and they allow one constructor to call another. The other ‘myth’ I had about readonly members is that you can set it’s value only once. This was busted as well (I recall Adam and Jamie’s show). Say you’ve initialized the readonly member through a variable initializer. You can over-write this value in any of the constructors any number of times. 1: public class Person 2: { 3: public int UniqueNumber { get; set; } 4: public string Name { get; set; } 5: public int Age { get; set; } 6: public DateTime DateOfBirth { get; set; } 7: public string InvoiceNumber { get; set; } 8:  9: private readonly string Alpha = "asdf"; 10: private readonly int Beta = 15; 11: private readonly double Delta = 0.077; 12: private readonly double Gamma = 1.0; 13:  14: public Person() 15: { 16: Alpha = "FDSA"; 17: Beta = 2; 18: Delta = 3.0; 19: Gamma = 0.0989; 20: } 21:  22: public Person(int uniqueNumber) : this() 23: { 24: UniqueNumber = uniqueNumber; 25: Beta = 3; 26: } 27:  28: public Person(string name, DateTime dob) : this() 29: { 30: Name = name; 31: DateOfBirth = dob; 32:  33: Alpha = ";LKJ"; 34: Gamma = 0.0898; 35: } 36:  37: public Person(int uniqueNumber, string name, int age, DateTime dob, string invoiceNumber) : this() 38: { 39: UniqueNumber = uniqueNumber; 40: Name = name; 41: Age = age; 42: DateOfBirth = dob; 43: InvoiceNumber = invoiceNumber; 44:  45: Alpha = "QWER"; 46: Beta = 5; 47: Delta = 1.0; 48: Gamma = 0.0; 49: } 50: } In the above example, every constructor over-writes the values for the readonly members. This is perfectly valid. There is a possibility that based on the way the object is instantiated, the readonly member will have a different value. Well, that’s all I have for today and read this as it’s on a related topic.

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  • Building applications with WCF - Intro

    - by skjagini
    I am going to write series of articles using Windows Communication Framework (WCF) to develop client and server applications and this is the first part of that series. What is WCF As Juwal puts in his Programming WCF book, WCF provides an SDK for developing and deploying services on Windows, provides runtime environment to expose CLR types as services and consume services as CLR types. Building services with WCF is incredibly easy and it’s implementation provides a set of industry standards and off the shelf plumbing including service hosting, instance management, reliability, transaction management, security etc such that it greatly increases productivity Scenario: Lets consider a typical bank customer trying to create an account, deposit amount and transfer funds between accounts, i.e. checking and savings. To make it interesting, we are going to divide the functionality into multiple services and each of them working with database directly. We will run test cases with and without transactional support across services. In this post we will build contracts, services, data access layer, unit tests to verify end to end communication etc, nothing big stuff here and we dig into other features of the WCF in subsequent posts with incremental changes. In any distributed architecture we have two pieces i.e. services and clients. Services as the name implies provide functionality to execute various pieces of business logic on the server, and clients providing interaction to the end user. Services can be built with Web Services or with WCF. Service built on WCF have the advantage of binding independent, i.e. can run against TCP and HTTP protocol without any significant changes to the code. Solution Services Profile: For creating a new bank customer, getting details about existing customer ProfileContract ProfileService Checking Account: To get checking account balance, deposit or withdraw amount CheckingAccountContract CheckingAccountService Savings Account: To get savings account balance, deposit or withdraw amount SavingsAccountContract SavingsAccountService ServiceHost: To host services, i.e. running the services at particular address, binding and contract where client can connect to Client: Helps end user to use services like creating account and amount transfer between the accounts BankDAL: Data access layer to work with database     BankDAL It’s no brainer not to use an ORM as many matured products are available currently in market including Linq2Sql, Entity Framework (EF), LLblGenPro etc. For this exercise I am going to use Entity Framework 4.0, CTP 5 with code first approach. There are two approaches when working with data, data driven and code driven. In data driven we start by designing tables and their constrains in database and generate entities in code while in code driven (code first) approach entities are defined in code and the metadata generated from the entities is used by the EF to create tables and table constrains. In previous versions the entity classes had  to derive from EF specific base classes. In EF 4 it  is not required to derive from any EF classes, the entities are not only persistence ignorant but also enable full test driven development using mock frameworks.  Application consists of 3 entities, Customer entity which contains Customer details; CheckingAccount and SavingsAccount to hold the respective account balance. We could have introduced an Account base class for CheckingAccount and SavingsAccount which is certainly possible with EF mappings but to keep it simple we are just going to follow 1 –1 mapping between entity and table mappings. Lets start out by defining a class called Customer which will be mapped to Customer table, observe that the class is simply a plain old clr object (POCO) and has no reference to EF at all. using System;   namespace BankDAL.Model { public class Customer { public int Id { get; set; } public string FullName { get; set; } public string Address { get; set; } public DateTime DateOfBirth { get; set; } } }   In order to inform EF about the Customer entity we have to define a database context with properties of type DbSet<> for every POCO which needs to be mapped to a table in database. EF uses convention over configuration to generate the metadata resulting in much less configuration. using System.Data.Entity;   namespace BankDAL.Model { public class BankDbContext: DbContext { public DbSet<Customer> Customers { get; set; } } }   Entity constrains can be defined through attributes on Customer class or using fluent syntax (no need to muscle with xml files), CustomerConfiguration class. By defining constrains in a separate class we can maintain clean POCOs without corrupting entity classes with database specific information.   using System; using System.Data.Entity.ModelConfiguration;   namespace BankDAL.Model { public class CustomerConfiguration: EntityTypeConfiguration<Customer> { public CustomerConfiguration() { Initialize(); }   private void Initialize() { //Setting the Primary Key this.HasKey(e => e.Id);   //Setting required fields this.HasRequired(e => e.FullName); this.HasRequired(e => e.Address); //Todo: Can't create required constraint as DateOfBirth is not reference type, research it //this.HasRequired(e => e.DateOfBirth); } } }   Any queries executed against Customers property in BankDbContext are executed against Cusomers table. By convention EF looks for connection string with key of BankDbContext when working with the context.   We are going to define a helper class to work with Customer entity with methods for querying, adding new entity etc and these are known as repository classes, i.e., CustomerRepository   using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CustomerRepository { private readonly IDbSet<Customer> _customers;   public CustomerRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _customers = bankDbContext.Customers; }   public IQueryable<Customer> Query() { return _customers; }   public void Add(Customer customer) { _customers.Add(customer); } } }   From the above code it is observable that the Query methods returns customers as IQueryable i.e. customers are retrieved only when actually used i.e. iterated. Returning as IQueryable also allows to execute filtering and joining statements from business logic using lamba expressions without cluttering the data access layer with tens of methods.   Our CheckingAccountRepository and SavingsAccountRepository look very similar to each other using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CheckingAccountRepository { private readonly IDbSet<CheckingAccount> _checkingAccounts;   public CheckingAccountRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _checkingAccounts = bankDbContext.CheckingAccounts; }   public IQueryable<CheckingAccount> Query() { return _checkingAccounts; }   public void Add(CheckingAccount account) { _checkingAccounts.Add(account); }   public IQueryable<CheckingAccount> GetAccount(int customerId) { return (from act in _checkingAccounts where act.CustomerId == customerId select act); }   } } The repository classes look very similar to each other for Query and Add methods, with the help of C# generics and implementing repository pattern (Martin Fowler) we can reduce the repeated code. Jarod from ElegantCode has posted an article on how to use repository pattern with EF which we will implement in the subsequent articles along with WCF Unity life time managers by Drew Contracts It is very easy to follow contract first approach with WCF, define the interface and append ServiceContract, OperationContract attributes. IProfile contract exposes functionality for creating customer and getting customer details.   using System; using System.ServiceModel; using BankDAL.Model;   namespace ProfileContract { [ServiceContract] public interface IProfile { [OperationContract] Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth);   [OperationContract] Customer GetCustomer(int id);   } }   ICheckingAccount contract exposes functionality for working with checking account, i.e., getting balance, deposit and withdraw of amount. ISavingsAccount contract looks the same as checking account.   using System.ServiceModel;   namespace CheckingAccountContract { [ServiceContract] public interface ICheckingAccount { [OperationContract] decimal? GetCheckingAccountBalance(int customerId);   [OperationContract] void DepositAmount(int customerId,decimal amount);   [OperationContract] void WithdrawAmount(int customerId, decimal amount);   } }   Services   Having covered the data access layer and contracts so far and here comes the core of the business logic, i.e. services.   .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } ProfileService implements the IProfile contract for creating customer and getting customer detail using CustomerRepository. using System; using System.Linq; using System.ServiceModel; using BankDAL; using BankDAL.Model; using BankDAL.Repositories; using ProfileContract;   namespace ProfileService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Profile: IProfile { public Customer CreateAccount( string customerName, string address, DateTime dateOfBirth) { Customer cust = new Customer { FullName = customerName, Address = address, DateOfBirth = dateOfBirth };   using (var bankDbContext = new BankDbContext()) { new CustomerRepository(bankDbContext).Add(cust); bankDbContext.SaveChanges(); } return cust; }   public Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth) { return CreateAccount(customerName, address, dateOfBirth); } public Customer GetCustomer(int id) { return new CustomerRepository(new BankDbContext()).Query() .Where(i => i.Id == id).FirstOrDefault(); }   } } From the above code you shall observe that we are calling bankDBContext’s SaveChanges method and there is no save method specific to customer entity because EF manages all the changes centralized at the context level and all the pending changes so far are submitted in a batch and it is represented as Unit of Work. Similarly Checking service implements ICheckingAccount contract using CheckingAccountRepository, notice that we are throwing overdraft exception if the balance falls by zero. WCF has it’s own way of raising exceptions using fault contracts which will be explained in the subsequent articles. SavingsAccountService is similar to CheckingAccountService. using System; using System.Linq; using System.ServiceModel; using BankDAL.Model; using BankDAL.Repositories; using CheckingAccountContract;   namespace CheckingAccountService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Checking:ICheckingAccount { public decimal? GetCheckingAccountBalance(int customerId) { using (var bankDbContext = new BankDbContext()) { CheckingAccount account = (new CheckingAccountRepository(bankDbContext) .GetAccount(customerId)).FirstOrDefault();   if (account != null) return account.Balance;   return null; } }   public void DepositAmount(int customerId, decimal amount) { using(var bankDbContext = new BankDbContext()) { var checkingAccountRepository = new CheckingAccountRepository(bankDbContext); CheckingAccount account = (checkingAccountRepository.GetAccount(customerId)) .FirstOrDefault();   if (account == null) { account = new CheckingAccount() { CustomerId = customerId }; checkingAccountRepository.Add(account); }   account.Balance = account.Balance + amount; if (account.Balance < 0) throw new ApplicationException("Overdraft not accepted");   bankDbContext.SaveChanges(); } } public void WithdrawAmount(int customerId, decimal amount) { DepositAmount(customerId, -1*amount); } } }   BankServiceHost The host acts as a glue binding contracts with it’s services, exposing the endpoints. The services can be exposed either through the code or configuration file, configuration file is preferred as it allows run time changes to service behavior even after deployment. We have 3 services and for each of the service you need to define name (the class that implements the service with fully qualified namespace) and endpoint known as ABC, i.e. address, binding and contract. We are using netTcpBinding and have defined the base address with for each of the contracts .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } <system.serviceModel> <services> <service name="ProfileService.Profile"> <endpoint binding="netTcpBinding" contract="ProfileContract.IProfile"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Profile"/> </baseAddresses> </host> </service> <service name="CheckingAccountService.Checking"> <endpoint binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Checking"/> </baseAddresses> </host> </service> <service name="SavingsAccountService.Savings"> <endpoint binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Savings"/> </baseAddresses> </host> </service> </services> </system.serviceModel> Have to open the services by creating service host which will handle the incoming requests from clients.   using System;   namespace ServiceHost { class Program { static void Main(string[] args) { CreateHosts(); Console.ReadLine(); }   private static void CreateHosts() { CreateHost(typeof(ProfileService.Profile),"Profile Service"); CreateHost(typeof(SavingsAccountService.Savings), "Savings Account Service"); CreateHost(typeof(CheckingAccountService.Checking), "Checking Account Service"); }   private static void CreateHost(Type type, string hostDescription) { System.ServiceModel.ServiceHost host = new System.ServiceModel.ServiceHost(type); host.Open();   if (host.ChannelDispatchers != null && host.ChannelDispatchers.Count != 0 && host.ChannelDispatchers[0].Listener != null) Console.WriteLine("Started: " + host.ChannelDispatchers[0].Listener.Uri); else Console.WriteLine("Failed to start:" + hostDescription); } } } BankClient    The client has no knowledge about service business logic other than the functionality it exposes through the contract, end points and a proxy to work against. The endpoint data and server proxy can be generated by right clicking on the project reference and choosing ‘Add Service Reference’ and entering the service end point address. Or if you have access to source, you can manually reference contract dlls and update clients configuration file to point to the service end point if the server and client happens to be being built using .Net framework. One of the pros with the manual approach is you don’t have to work against messy code generated files.   <system.serviceModel> <client> <endpoint name="tcpProfile" address="net.tcp://localhost:1000/Profile" binding="netTcpBinding" contract="ProfileContract.IProfile"/> <endpoint name="tcpCheckingAccount" address="net.tcp://localhost:1000/Checking" binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <endpoint name="tcpSavingsAccount" address="net.tcp://localhost:1000/Savings" binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/>   </client> </system.serviceModel> The client uses a façade to connect to the services   using System.ServiceModel; using CheckingAccountContract; using ProfileContract; using SavingsAccountContract;   namespace Client { public class ProxyFacade { public static IProfile ProfileProxy() { return (new ChannelFactory<IProfile>("tcpProfile")).CreateChannel(); }   public static ICheckingAccount CheckingAccountProxy() { return (new ChannelFactory<ICheckingAccount>("tcpCheckingAccount")) .CreateChannel(); }   public static ISavingsAccount SavingsAccountProxy() { return (new ChannelFactory<ISavingsAccount>("tcpSavingsAccount")) .CreateChannel(); }   } }   With that in place, lets get our unit tests going   using System; using System.Diagnostics; using BankDAL.Model; using NUnit.Framework; using ProfileContract;   namespace Client { [TestFixture] public class Tests { private void TransferFundsFromSavingsToCheckingAccount(int customerId, decimal amount) { ProxyFacade.CheckingAccountProxy().DepositAmount(customerId, amount); ProxyFacade.SavingsAccountProxy().WithdrawAmount(customerId, amount); }   private void TransferFundsFromCheckingToSavingsAccount(int customerId, decimal amount) { ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, amount); ProxyFacade.CheckingAccountProxy().WithdrawAmount(customerId, amount); }     [Test] public void CreateAndGetProfileTest() { IProfile profile = ProxyFacade.ProfileProxy(); const string customerName = "Tom"; int customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)).Id; Customer customer = profile.GetCustomer(customerId); Assert.AreEqual(customerName,customer.FullName); }   [Test] public void DepositWithDrawAndTransferAmountTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Smith" + DateTime.Now.ToString("HH:mm:ss"); var customer = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)); // Deposit to Savings ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 100); ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 25); Assert.AreEqual(125, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); // Withdraw ProxyFacade.SavingsAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(95, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id));   // Deposit to Checking ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 60); ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 40); Assert.AreEqual(100, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); // Withdraw ProxyFacade.CheckingAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(70, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Savings to Checking TransferFundsFromSavingsToCheckingAccount(customer.Id,10); Assert.AreEqual(85, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Checking to Savings TransferFundsFromCheckingToSavingsAccount(customer.Id, 50); Assert.AreEqual(135, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(30, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); }   [Test] public void FundTransfersWithOverDraftTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Angelina" + DateTime.Now.ToString("HH:mm:ss");   var customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1972, 1, 1)).Id;   ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, 100); TransferFundsFromSavingsToCheckingAccount(customerId,80); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId));   try { TransferFundsFromSavingsToCheckingAccount(customerId,30); } catch (Exception e) { Debug.WriteLine(e.Message); }   Assert.AreEqual(110, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId)); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); } } }   We are creating a new instance of the channel for every operation, we will look into instance management and how creating a new instance of channel affects it in subsequent articles. The first two test cases deals with creation of Customer, deposit and withdraw of month between accounts. The last case, FundTransferWithOverDraftTest() is interesting. Customer starts with depositing $100 in SavingsAccount followed by transfer of $80 in to checking account resulting in $20 in savings account.  Customer then initiates $30 transfer from Savings to Checking resulting in overdraft exception on Savings with $30 being deposited to Checking. As we are not running both the requests in transactions the customer ends up with more amount than what he started with $100. In subsequent posts we will look into transactions handling.  Make sure the ServiceHost project is set as start up project and start the solution. Run the test cases either from NUnit client or TestDriven.Net/Resharper which ever is your favorite tool. Make sure you have updated the data base connection string in the ServiceHost config file to point to your local database

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  • NullReferenceException when accessing variables in a 2D array in Unity

    - by Syed
    I have made a class including variables in Monodevelop which is: public class GridInfo : MonoBehaviour { public float initPosX; public float initPosY; public bool inUse; public int f; public int g; public int h; public GridInfo parent; public int y,x; } Now I am using its class variable in another class, Map.cs which is: public class Map : MonoBehaviour { public static GridInfo[,] Tile = new GridInfo[17, 23]; void Start() { Tile[0,0].initPosX = initPosX; //Line 49 } } I am not getting any error on runtime, but when I play in unity it is giving me error NullReferenceException: Object reference not set to an instance of an object Map.Start () (at Assets/Scripts/Map.cs:49) I am not inserting this script in any gameobject, as Map.cs will make a GridInfo type array, I have also tried using variables using GetComponent, where is the problem ?

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  • Unable to access A class variables in B Class - Unity-Monodevelop

    - by Syed
    I have made a class including variables in Monodevelop which is: public class GridInfo : MonoBehaviour { public float initPosX; public float initPosY; public bool inUse; public int f; public int g; public int h; public GridInfo parent; public int y,x; } Now I am using its class variable in another class, Map.cs which is: public class Map : MonoBehaviour { public static GridInfo[,] Tile = new GridInfo[17, 23]; void Start() { Tile[0,0].initPosX = initPosX; //Line 49 } } Iam not getting any error on runtime, but when I play in unity it is giving me error NullReferenceException: Object reference not set to an instance of an object Map.Start () (at Assets/Scripts/Map.cs:49) I am not inserting this script in any gameobject, as Map.cs will make a GridInfo type array, I have also tried using variables using GetComponent, where is the problem ?

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  • Does a mobile app need more access than the public API of a site?

    - by Iain
    I have a site with a public API, and some mobile app developers have been brought in to produce an iPhone app for the site. They insist they need to see the database schema, but as I understand it, they should only need access to the documented public API. Am I right? Is there something I've missed? I've told them that if there's a feature missing or data they require I can extend the API so that they can access it. I thought a web service API held to much the same principles as OOP object API's, in that the implementation details should be hidden as much as possible. I'm not a mobile app developer so if there is something I don't quite see then please let me know. Any insight or help will be much appreciated.

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  • Public Cloud, co-location and managed services ... what is the cloud?

    - by llaszews
    Recently I have had conversation with a number of people that are selling and implementing 'cloud' solutions. I put cloud in quotes as implementations like co-location (aka co-lo) and managed services (sometimes referred to as 'your mess for less') have become popular options for companies moving to the cloud. These are obviously not pure public cloud offerings and probably more of hybrid cloud implementations as the infrastructure (PasS and IaaS)is dedicated to a specific customer. This eliminates the security, multi-tenancy, performance and other concerns that companies have regarding public cloud. Are co-location and managed services cloud to you? Are they something your company is considering when you think about cloud ?

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  • How do you describe your profession in a public place or conference?

    - by Jenko
    I've often been in situations where non-technical people ask me, "So, what do you do?" ... and I've found it somewhat hard to describe that I spend the entirely of my days pouring over colored text. Of course, its quite reasonable to say "I design software" or "I develop computer applications", but that still feels somewhat "lame" and generic. So how do you describe your profession in public situations? are there any insights for those of us less gifted in public speaking?

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