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  • How to save errors with the handleError in CakePHP 2.0?

    - by jags1988cr
    I have a big problem. Well, I'm trying to save the errors that happen in my web application. For example (only a example), if I make a division by zero, or happens an error in a query or something like that. So, I wanna catch that and save it in the database. But the handleError of CakePHP is static, so I can't use $this-MyModel-saveError(...). In my /app/Lib/AppError.php I have this: class AppError extends ErrorHandler { public $uses = array('Errors.Error'); public static function handleError($code, $description, $file = null, $line = null, $context = null) { //This print the error: echo "Code: ".$code." Description: ".$description." File: ".$file." Line: ".$line."<br>"; //I want to do this, (save to the database): $this->Error->saveError($code, $description, $file, $line); } } Without the $this-Error-saveError($code, $description, $file, $line); it works but I not only want to show the error. I think need an example or something like that. Please help me. Regards and thank you. Thanks... P.D.: Sorry for the English, I'm an english student...

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  • Saving associated domain classes in Grails

    - by Cesar
    I'm struggling to get association right on Grails. Let's say I have two domain classes: class Engine { String name int numberOfCylinders = 4 static constraints = { name(blank:false, nullable:false) numberOfCylinders(range:4..8) } } class Car { int year String brand Engine engine = new Engine(name:"Default Engine") static constraints = { engine(nullable:false) brand(blank:false, nullable:false) year(nullable:false) } } The idea is that users can create cars without creating an engine first, and those cars get a default engine. In the CarController I have: def save = { def car = new Car(params) if(!car.hasErrors() && car.save()){ flash.message = "Car saved" redirect(action:index) }else{ render(view:'create', model:[car:car]) } } When trying to save, I get a null value exception on the Car.engine field, so obviously the default engine is not created and saved. I tried to manually create the engine: def save = { def car = new Car(params) car.engine = new Engine(name: "Default Engine") if(!car.hasErrors() && car.save()){ flash.message = "Car saved" redirect(action:index) }else{ render(view:'create', model:[car:car]) } } Didn't work either. Is Grails not able to save associated classes? How could I implement such feature?

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  • Call from a singleton class to a function which in turn calls that class's method

    - by dare2be
    Hello, I am still looking for a way to phrase it properly (I'm not a native speaker...). So I have this class SQL which implements the singleton pattern (for obvious reasons) and I also have this function, checkUsr(), which queries the database using one of SQL's methods. Everything works fine as long as I don't call checkUsr() from within the SQL class. When I do so, the scripts just exits and a blank page is displayed - no errors are returned, no exception is thrown... What's happening? And how do I work around this problem? EDIT: class SQL { public static function singleton() { static $instance; if(!isset($instance)) $instance = new SQL; return $instance; } public function tryLoginAuthor( $login, $sha1 ) { (...) } } function checkUsr() { if (!isset($_SESSION['login']) || !isset($_SESSION['sha1'])) throw new Exception('Not logged in', 1); $SQL = SQL::singleton(); $res = $SQL->tryLoginAuthor($_SESSION['login'], $_SESSION['sha1']); if (!isset($res[0])) throw new Exception('Not logged in', 1); }

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  • Question about singleton property

    - by Jack
    I'm reading the java tutorial for enums located here and have a question: http://java.sun.com/j2se/1.5.0/docs/guide/language/enums.html#Card The part i'm confused about is as follows: "The Card class, above, contains a static factory that returns a deck, but there is no way to get an individual card from its rank and suit. Merely exposing the constructor would destroy the singleton property (that only a single instance of each card is allowed to exist). Here is how to write a static factory that preserves the singleton property, using a nested EnumMap: " Now as I understand, changing the original private "Card" constructor to public would allow us to instantiate an unlimited number of copies of a "Card" object with a given suit+rank. The solution as proposed was to create an EnumMap which would store four Maps (one for each suit), which themselves contained 13 Card objects with the rank as their keys. And so now if you wanted to retrieve a specific Card object from the deck, you would just call the "valueOf" method. My question now is, what's the prevent you with calling the valueOf method as many times as you like? Wouldn't that lead to the same problem as making the original private constructor public? Thanks.

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  • how are association, aggregation and composition written?

    - by ajsie
    i have read some posts about the differences between these 3 relationships and i think i get the point. i just wonder, are all these written the same when coding? question 1: all 3 are just a value of the object type in a instance variable? class A { public $b = '' public function __construct($object) { $this->b = $object // <-- could be a association, aggregation or a composition relation? } } question 2: does it have to be an instance variable or can it be a static one? class A { public static $b = '' // <-- nothing changed? public function __construct($object) { $this->b = $object } } question 3: is there a difference in where the object is created? i tend to think that composition object is created inside the object: class A { public $b = '' public function __construct() { $this->b = new Object // is created inside the object } } and aggregation/association is passed through a constructor or another method: class A { public $b = '' public function __construct($object) { // passed through a method $this->b = $object } } question 4: why/when is this important to know. do i have to comment an object inside another what relation its about or do you do it in an UML diagram? could someone shed a light on these questions. thanks!

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  • Mono Develop 2.4.1 + linq error.

    - by Nev_Rahd
    I just started to learn Mono Develop Installed Mono Develop 2.4.1 and trial version of Mono Touch. my Code: using System; using System.Xml.Linq; using System.Collections.Generic; namespace RSSReader { public static class RSSRepository { public static IList<FeedItem> GetFeeds(string url) { XDocument rssFeed = XDocument.Load(url); Console.Write(rssFeed.ToString()); var feeds = new List<FeedItem>(); try { var query = from item in rssFeed.Descendants("item") select new FeedItem { Title = item.Element("title").Value, Published = DateTime.Parse(item.Element("pubDate").Value), Url = item.Element("link").Value }; feeds = query.ToList(); } catch (Exception ex){ Console.WriteLine(ex.Message); } return feeds; } } } This is throwing an error: An implementation of 'select' query expression pattern could not be found. Are you missing 'System.linq' using directive or 'System.Core.dll' assembly reference? I got both references to System.Xml.Linq and System.Core What am i missing ?

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  • Why aren't my threads start at the same time? Java

    - by Ada
    Hi, I have variable number of threads which are used for parallel downloading. I used this, for(int i = 0; i< sth; i++){ thrList.add(new myThread (parameters)); thrList.get(i).start(); thrList.get(i).join(); } I don't know why but they wait for each other to complete. When using threads, I am supposed get mixed print outs, since right then there are several threads running that code. However, when I print them out, they are always in order and one thread waits for the previous one to finish first. I only want them to join the main thread, not wait for each other. I noticed that when I measured time while downloading in parallel. How can I fix this? Why are they doing it in order? In my .java, there is MyThread class with run and there is Downloader class with static methods and variables. Would they be the cause of this? The static methods and variables? How can I fix this problem?

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  • Operator overloading in generic struct: can I create overloads for specific kinds(?) of generic?

    - by Carson Myers
    I'm defining physical units in C#, using generic structs, and it was going okay until I got the error: One of the parameters of a binary operator must be the containing type when trying to overload the mathematical operators so that they convert between different units. So, I have something like this: public interface ScalarUnit { } public class Duration : ScalarUnit { } public struct Scalar<T> where T : ScalarUnit { public readonly double Value; public Scalar(double Value) { this.Value = Value; } public static implicit operator double(Scalar<T> Value) { return Value.Value; } } public interface VectorUnit { } public class Displacement : VectorUnit { } public class Velocity : VectorUnit { } public struct Vector<T> where T : VectorUnit { #... public static Vector<Velocity> operator /(Vector<Displacement> v1, Scalar<Duration> v2) { return new Vector<Velocity>(v1.Magnitude / v2, v1.Direction); } } There aren't any errors for the + and - operators, where I'm just working on a Vector<T>, but when I substitute a unit for T, suddenly it doesn't like it. Is there a way to make this work? I figured it would work, since Displacement implements the VectorUnit interface, and I have where T : VectorUnit in the struct header. Am I at least on the right track here? I'm new to C# so I have difficulty understanding what's going on sometimes.

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  • Cast exception being generated when using the same type of object

    - by David Tunnell
    I was previously using static variables to hold variable data that I want to save between postbacks. I was having problems and found that the data in these variables is lost when the appdomain ends. So I did some research and decided to go with ViewStates: static Dictionary<string, linkButtonObject> linkButtonDictonary; protected void Page_Load(object sender, EventArgs e) { if (ViewState["linkButtonDictonary"] != null) { linkButtonDictonary = (Dictionary<string, linkButtonObject>)ViewState["linkButtonDictonary"]; } else { linkButtonDictonary = new Dictionary<string, linkButtonObject>(); } } And here is the very simple class I use: [Serializable] public class linkButtonObject { public string storyNumber { get; set; } public string TaskName { get; set; } } I am adding to linkButtonDictionary as a gridview is databound: protected void hoursReportGridView_OnRowDataBound(Object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.DataRow) { LinkButton btn = (LinkButton)e.Row.FindControl("taskLinkButton"); linkButtonObject currentRow = new linkButtonObject(); currentRow.storyNumber = e.Row.Cells[3].Text; currentRow.TaskName = e.Row.Cells[5].Text; linkButtonDictonary.Add(btn.UniqueID, currentRow); } } It appears that my previous issues are resolved however a new one has arisin. Sometime when I postback I am getting this error: [A]System.Collections.Generic.Dictionary2[System.String,linkButtonObject] cannot be cast to [B]System.Collections.Generic.Dictionary2[System.String,linkButtonObject]. Type A originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. Type B originates from 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' in the context 'LoadNeither' at location 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'. I don't understand how there can be a casting issue when I am using the same class everywhere. What am I doing wrong and how do I fix it?

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  • Calling an Overridden Method from a Parent-Class Constructor

    - by Vaibhav Bajpai
    I tried calling an overridden method from a constructor of a parent class and noticed different behavior across languages. C++ - echoes A.foo() class A{ public: A(){foo();} virtual void foo(){cout<<"A.foo()";} }; class B : public A{ public: B(){} void foo(){cout<<"B.foo()";} }; int main(){ B *b = new B(); } Java - echoes B.foo() class A{ public A(){foo();} public void foo(){System.out.println("A.foo()");} } class B extends A{ public void foo(){System.out.println("B.foo()");} } class Demo{ public static void main(String args[]){ B b = new B(); } } C# - echoes B.foo() class A{ public A(){foo();} public virtual void foo(){Console.WriteLine("A.foo()");} } class B : A{ public override void foo(){Console.WriteLine("B.foo()");} } class MainClass { public static void Main (string[] args) { B b = new B(); } } I realize that in C++ objects are created from top-most parent going down the hierarchy, so when the constructor calls the overridden method, B does not even exist, so it calls the A' version of the method. However, I am not sure why I am getting different behavior in Java and C#.

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  • How do I handle freeing unmanaged structures in C# on application close?

    - by LostKaleb
    I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } } Thanks in advance!

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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • How do I pass three arrays from on method to another?

    - by user2966716
    I have a method studentSummary, that scans the input and creates three arrays examMark,courseworkMark and courseworkWeight. I need these arrays passing over to a different method, so I can use them to calculate moduleResult. heres my code: public static int[] studentSummary(int[] courseworkWeight2, int [] examMark2 , int [] courseworkMark2){ int examMark[] = { 0, 0, 0, 0, 0, 0 }; int courseworkMark[] = { 0, 0, 0, 0, 0, 0 }; Scanner resultInput = new Scanner(System.in); int courseworkWeight[] = { 0, 0, 0, 0, 0, 0 }; for (int k = 1; k < 7; k++) { System.out.print("Please enter exam marks for module " + k + ":"); examMark[k - 1] = resultInput.nextInt(); System.out.print("Please enter Coursework marks for module " + k + ":"); courseworkMark[k - 1] = resultInput.nextInt(); System.out.print("Please enter Coursework weighting for module " + k + ":"); courseworkWeight[k - 1] = resultInput.nextInt(); } Calculator method: public static int[] markCalculator() { int[] courseworkWeight = new int [6]; int[] courseworkMark = new int [6]; int[] examMark = new int [6]; for (int i = 0; i < 6; i++) { computedModuleMark = ((courseworkMark[i] * courseworkWeight[i]) + (examMark[i] * (100 - courseworkWeight[i]))) / 100; if ((computedModuleMark) < 35) { if (examMark[i]<35){ } } moduleMark[i] = computedModuleMark; } computeResult(moduleMark); StudentChart.draw(moduleMark); StudentChart.printSummary(moduleMark); return moduleMark; }

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  • Looking for an appropriate design pattern

    - by user1066015
    I have a game that tracks user stats after every match, such as how far they travelled, how many times they attacked, how far they fell, etc, and my current implementations looks somewhat as follows (simplified version): Class Player{ int id; public Player(){ int id = Math.random()*100000; PlayerData.players.put(id,new PlayerData()); } public void jump(){ //Logic to make the user jump //... //call the playerManager PlayerManager.jump(this); } public void attack(Player target){ //logic to attack the player //... //call the player manager PlayerManager.attack(this,target); } } Class PlayerData{ public static HashMap<int, PlayerData> players = new HashMap<int,PlayerData>(); int id; int timesJumped; int timesAttacked; } public void incrementJumped(){ timesJumped++; } public void incrementAttacked(){ timesAttacked++; } } Class PlayerManager{ public static void jump(Player player){ players.get(player.getId()).incrementJumped(); } public void incrementAttacked(Player player, Player target){ players.get(player.getId()).incrementAttacked(); } } So I have a PlayerData class which holds all of the statistics, and brings it out of the player class because it isn't part of the player logic. Then I have PlayerManager, which would be on the server, and that controls the interactions between players (a lot of the logic that does that is excluded so I could keep this simple). I put the calls to the PlayerData class in the Manager class because sometimes you have to do certain checks between players, for instance if the attack actually hits, then you increment "attackHits". The main problem (in my opinion, correct me if I'm wrong) is that this is not very extensible. I will have to touch the PlayerData class if I want to keep track of a new stat, by adding methods and fields, and then I have to potentially add more methods to my PlayerManager, so it isn't very modulized. If there is an improvement to this that you would recommend, I would be very appreciative. Thanks.

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  • How to create a String Array and link it to a Grade array

    - by user1861544
    I have a project that I need to create 2 Arrays, one to hold Student Names and one to hold Student Scores. The user inputs the size of the array, and the array needs to be sorted using BubbleSort (putting the high scores at the top). I have started the project, created the first array for scores, I have successfully done bubble sort and sorted the grades. Now I can't figure out how to make an array for Names, and once I do how do I make the names array correspond to the Grades array BubbleSort? Here is the code I have so far. import java.util.Scanner; public class Grades { public static void main(String[]args){ { Scanner UserIn = new Scanner(System.in); System.out.print( "How many students are there? " ); int[]GradeArray = new int[UserIn.nextInt()]; for( int i=0 ; i<GradeArray.length ; i++ ) { System.out.print( "Enter Grade for Student " + (i+1) + ": " ); GradeArray[i] = UserIn.nextInt(); } bubbleSort(GradeArray); for( int i : GradeArray ) System.out.println( i ); System.out.println(); } } private static void bubbleSort(int[]GradeArray){ int n = GradeArray.length; int temp = 0; String temp2; for(int i=0; i<n; i++){ for(int j=1; j<(n-i);j++){ if(GradeArray[j-1]<GradeArray[j]){ //swap temp=GradeArray[j-1]; GradeArray[j-1]=GradeArray[j]; GradeArray[j]=temp; } } } } } Also how do I change the grades to Double? I started with Int and when I try to change everything to double I get an error saying "Found Double, expected Int".

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  • Global State and Singletons Dependency injection

    - by Manu
    this is a problem i face lot of times when i am designing a new app i'll use a sample problem to explain this think i am writing simple game.so i want to hold a list of players. i have few options.. 1.use a static field in some class private static ArrayList<Player> players = new ArrayList<Integer>(); public Player getPlayer(int i){ return players.get(i); } but this a global state 2.or i can use a singleton class PlayerList{ private PlayerList instance; private PlayerList(){...} public PlayerList getInstance() { if(instance==null){ ... } return instance; } } but this is bad because it's a singleton 3.Dependency injection class Game { private PlayerList playerList; public Game(PlayerList list) { this.list = list; } public PlayerList getPlayerList() { return playerList; } } this seems good but it's not, if any object outside Game need to look at PlayerList (which is the usual case) i have to use one of the above methods to make the Game class available globally. so I just add another layer to the problem. didn't actually solve anything. what is the optimum solution ? (currently i use Singleton approach)

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  • Creating UIButtons

    - by Ralphonzo
    During loadView I am creating 20 UIButtons that I would like to change the title text of depending on the state of a UIPageControl. I have a pre-save plist that is loaded into a NSArray called arrChars on the event of the current page changing, I set the buttons titles to their relevant text title from the array. The code that does this is: for (int i = 1; i < (ButtonsPerPage + 1); i++) { UIButton *uButton = (UIButton *)[self.view viewWithTag:i]; if(iPage == 1) { iArrPos = (i - 1); } else { iArrPos = (iPage * ButtonsPerPage) + (i - 1); } [uButton setAlpha:0]; NSLog(@"Trying: %d of %d", iArrPos, [self.arrChars count]); if (iArrPos >= [self.arrChars count]) { [uButton setTitle: @"" forState: UIControlStateNormal]; } else { NSString *value = [[NSString alloc] initWithFormat:@"%@", [self.arrChars objectAtIndex:iArrPos]]; NSLog(@"%@", value); [uButton setTitle: [[NSString stringWithFormat:@"%@", value] forState: UIControlStateNormal]; [value release]; //////Have tried: //////[uButton setTitle: value forState: UIControlStateNormal]; //////Have also tried: //////[uButton setTitle: [self.arrChars objectAtIndex:iArrPos] forState: UIControlStateNormal]; //////Have also also tried: //////[uButton setTitle: [[self.arrChars objectAtIndex:iArrPos] autorelease] forState: UIControlStateNormal]; } [uButton setAlpha:1]; } When setting the Title of a button it does not appear to be autoreleasing the previous title and the allocation goes up and up. What am I doing wrong? I have been told before that tracking things by allocations is a bad way to chase leaks because as far as I can see, the object is not leaking in Instruments but my total living allocations continue to climb until I get a memory warning. If there is a better way to track there I would love to know.

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  • How do I remove an old JPanel and add a new one?

    - by Roman
    I would like to remove an old JPanel from the Window (JFrame) and add a new one. How should I do it? I tried the following: public static void showGUI() { JFrame frame = new JFrame("Colored Trails"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(partnerSelectionPanel); frame.setSize(600,400); frame.setVisible(true); } private static void updateGUI(final int i, final JLabel label, final JPanel partnerSelectionPanel) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText(i + " seconds left."); } partnerSelectionPanel.setVisible(false); \\ <------------ } ); } So, my code update the "old" JPanel and them it makes the whole JPanel invisible. It was the idea. But it does not work. The compiler complains about the line indicated with "<------------". It writes: <identifier> expected, illegal start of type.

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  • C++ traits question

    - by duli
    I have a templated class template <typename Data> class C { ..... } In most situations, I depend on the compiler to let me substitute types for Data. I call methods foo(), goo() on objects of type Data, so what I substitute needs to provide that. I now need to substitute int and string for my Data type. I do not want to specialize because the class is already too big and would require specializing each method (with only small code change). My options (please tell me if there are more) 1) I can provide wrapper classes around int and string which implement the methods foo(), goo() etc 2) provide a traits class traits that calls foo() or goo() on objects of classes that provide foo(),goo() (these are my present substitutable classes) and specialize these classes for int and string. Questions 1) what are the relative merits of 1 vs 2? 2) My traits classes will have static methods. Can a traits class have non-static methods as well? I see most traits classes define constants in the STL. 3) Do I make the traits classes global or should I pass them in as a template parameter for class C?

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  • Why can't I dynamically add rows to a HTML table using JavaScript in Internet Explorer?

    - by karlthorwald
    In Firefox it works, in my Internet Explorer 6 or 7 it doesn't: <html> <head> <script type="text/javascript"> function newLine() { var tdmod = document.createElement('td'); tdmod.appendChild(document.createTextNode("dynamic")); var tr = document.createElement('tr'); tr.appendChild(tdmod); var tt = document.getElementById("t1"); tt.appendChild(tr); } </script> </head> <body> <a href="#" onclick="newLine()">newLine</a> <table id="t1" border="1"> <tr> <td> static </td> </tr> </table> </body> The user clicks on the link "newLine" and new rows should be added to the table. How to make this work also in IE? Edit: Thanks to the accepted answer I changed it like this and now it works: <table border="1"> <tbody id="t1"> <tr> <td> static </td> </tr> </tbody> </table>

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  • WPF binding problem

    - by Lolo
    I've got problem with binding in XAML/WPF. I created Action class witch extends FrameworkElement. Each Action has list of ActionItem. The problem is that the Data/DataContext properties of ActionItem are not set, so they are always null. XAML: <my:Action DataContext="{Binding}"> <my:Action.Items> <my:ActionItem DataContext="{Binding}" Data="{Binding}" /> </my:Action.Items> </my:Action> C#: public class Action : FrameworkElement { public static readonly DependencyProperty ItemsProperty = DependencyProperty.Register("Items", typeof(IList), typeof(Action), new PropertyMetadata(null, null), null); public Action() { this.Items = new ArrayList(); this.DataContextChanged += (s, e) => MessageBox.Show("Action.DataContext"); } public IList Items { get { return (IList)this.GetValue(ItemsProperty); } set { this.SetValue(ItemsProperty, value); } } } public class ActionItem : FrameworkElement { public static readonly DependencyProperty DataProperty = DependencyProperty.Register("Data", typeof(object), typeof(ActionItem), new PropertyMetadata( null, null, (d, v) => { if (v != null) MessageBox.Show("ActionItem.Data is not null"); return v; } ), null ); public object Data { get { return this.GetValue(DataProperty); } set { this.SetValue(DataProperty, value); } } public ActionItem() { this.DataContextChanged += (s, e) => MessageBox.Show("ActionItem.DataContext"); } } Any ideas?

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  • Dispose, when is it called?

    - by Snake
    Consider the following code: namespace DisposeTest { using System; class Program { static void Main(string[] args) { Console.WriteLine("Calling Test"); Test(); Console.WriteLine("Call to Test done"); } static void Test() { DisposeImplementation di = new DisposeImplementation(); } } internal class DisposeImplementation : IDisposable { ~DisposeImplementation() { Console.WriteLine("~ in DisposeImplementation instance called"); } public void Dispose() { Console.WriteLine("Dispose in DisposeImplementation instance called"); } } } The Dispose just never get's called, even if I put a wait loop after the Test(); invocation. So that quite sucks. I want to write a class that is straightforward and very easy to use, to make sure that every possible resource is cleaned up. I don't want to put that responsibilty to the user of my class. Possible solution: use using, or call Dispose myself(basicly the same). Can I force the user to use a using? Or can I force the dispose to be called? Calling GC.Collect(); after Test(); doesn't work either. Putting di to null doesn't invoke Dispose either. The Deconstructor DOES work, so the object get's deconstructed when it exits Test()

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  • Does std::vector change its address? How to avoid

    - by kunigami
    Since vector elements are stored contiguously, I guess it may not have the same address after some push_back's , because the initial allocated space could not suffice. I'm working on a code where I need a reference to an element in a vector, like: int main(){ vector<int> v; v.push_back(1); int *ptr = &v[0]; for(int i=2; i<100; i++) v.push_back(i); cout << *ptr << endl; //? return 0; } But it's not necessarily true that ptr contains a reference to v[0], right? How would be a good way to guarantee it? My first idea would be to use a vector of pointers and dynamic allocation. I'm wondering if there's an easier way to do that? PS.: Actually I'm using a vector of a class instead of int, but I think the issues are the same.

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  • Create table class as a singleton

    - by Mark
    I got a class that I use as a table. This class got an array of 16 row classes. These row classes all have 6 double variables. The values of these rows are set once and never change. Would it be a good practice to make this table a singleton? The advantage is that it cost less memory, but the table will be called from multiple threads so I have to synchronize my code which way cause a bit slower application. However lookups in this table are probably a very small portion of the total code that is executed. EDIT: This is my code, are there better ways to do this or is this a good practice? Removed synchronized keyword according to recommendations in this question. final class HalfTimeTable { private HalfTimeRow[] table = new HalfTimeRow[16]; private static final HalfTimeTable instance = new HalfTimeTable(); private HalfTimeTable() { if (instance != null) { throw new IllegalStateException("Already instantiated"); } table[0] = new HalfTimeRow(4.0, 1.2599, 0.5050, 1.5, 1.7435, 0.1911); table[1] = new HalfTimeRow(8.0, 1.0000, 0.6514, 3.0, 1.3838, 0.4295); //etc } @Override @Deprecated public Object clone() throws CloneNotSupportedException { throw new CloneNotSupportedException(); } public static HalfTimeTable getInstance() { return instance; } public HalfTimeRow getRow(int rownumber) { return table[rownumber]; } }

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  • why doesnt this program print?

    - by Alex
    What I'm trying to do is to print my two-dimensional array but i'm lost. The first function is running perfect, the problem is the second or maybe the way I'm passing it to the "Print" function. #include <stdio.h> #include <stdlib.h> #define ROW 2 #define COL 2 //Memory allocation and values input void func(int **arr) { int i, j; arr = (int**)calloc(ROW,sizeof(int*)); for(i=0; i < ROW; i++) arr[i] = (int*)calloc(COL,sizeof(int)); printf("Input: \n"); for(i=0; i<ROW; i++) for(j=0; j<COL; j++) scanf_s("%d", &arr[i][j]); } //This is where the problem begins or maybe it's in the main void print(int **arr) { int i, j; for(i=0; i<ROW; i++) { for(j=0; j<COL; j++) printf("%5d", arr[i][j]); printf("\n"); } } void main() { int *arr; func(&arr); print(&arr); //maybe I'm not passing the arr right ? }

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