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• How to get child nodes after store load

  - by Azincourt

  Version: ExtJs 4.1 To change the child items I use this function: TreeStore (Ext.data.TreeStore) storeId : 'treeStore', ... constructor: function( oConfig ) { ... this.on( 'expand', function( oObj ) { oObj.eachChild(function(oNode) { switch(oNode.data.type) { case "report": oNode.set('icon', strIconReport); break; case "view": oNode.set('icon', strIconView); break; } }); }); Reload After removing or adding items in the tree, I reload the tree somewhere else with: var oStore = Ext.getStore('treeStore'); oStore.load({ node : oNode, params : { newpath : oNode.data.path, overwrite : true } }); Although it is the same store treeStore, after loading and expanding to the correct path, the icons are not changed since the .on( 'expand') function is not called. Why? Question How can I change the icons of this newly loaded store before it expands to the node path? What I tried Before calling .load() I tried to edit the children with oNode.eachChild(function(oChild) {} but no success.

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• iOS layout; I'm not getting it

  - by Tbee

  Well, "not getting it" is too harsh; I've got it working in for what for me is a logical setup, but it does not seem to be what iOS deems logical. So I'm not getting something. Suppose I've got an app that shows two pieces of information; a date and a table. According to the MVC approach I've got three MVC at work here, one for the date, one for the table and one that takes both these MCVs and makes it into a screen, wiring them up. The master MVC knows how/where it wants to layout the two sub MVC's. Each detail MVC only takes care of its own childeren within the bounds that were specified by the master MVC. Something like: - (void)loadView { MVC* mvc1 = [[MVC1 alloc] initwithFrame:...] [self.view addSubview:mvc1.view]; MVC* mvc2 = [[MVC2 alloc] initwithFrame:...] [self.view addSubview:mvc2.view]; } If the above is logical (which is it for me) then I would expect any MVC class to have a constructor "initWithFrame". But an MVC does not, only view have this. Why? How would one correctly layout nested MVCs? (Naturally I do not have just these two, but the detail MVCs have sub MVCs again.)

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• XNA: What can cause SpriteBatch.End() to throw a NRE?

  - by Rosarch

  I don't understand what I'm doing wrong here: public void Draw(GameTime gameTime) // in ScreenManager { SpriteBatch.Begin(SpriteBlendMode.AlphaBlend); for (int i = 0; i < Screens.Count; i++) { if (Screens[i].State == Screen.ScreenState.HIDDEN) continue; Screens[i].Draw(gameTime); } SpriteBatch.End(); // null ref exception } SpriteBatch itself is not null. Some more context: public class MasterEngine : Microsoft.Xna.Framework.Game { public MasterEngine() { graphicsDeviceManager = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); // ... spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); screenManager = new ScreenManager(assets, gameEngine, graphicsDeviceManager.GraphicsDevice, spriteBatch); } //... protected override void Draw(GameTime gameTime) { screenManager.Draw(gameTime); // calls the problematic method base.Draw(gameTime); } } Am I failing to initialize something properly? UPDATE: As an experiment, I tried this to the constructor of MasterEngine: spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); spriteBatch.Begin(); spriteBatch.DrawString(assets.GetAsset<SpriteFont>("calibri"), "ftw", new Vector2(), Color.White); spriteBatch.End(); This does not cause a NRE. hmm.... UPDATE 2: This does cause an NRE: protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.End(); // boned here //screenManager.Draw(gameTime); base.Draw(gameTime); }

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• Flash compiler error 1061: Call to a possibly undefined method run... but run exists!

  - by Zane Geiger

  So I've been working on making a game in Processing but I think Flash would be a better way to get more people playing it, so I've decided to learn Flash. The problem is that I keep getting really stupid errors on incredibly simple things. For instance, I want to make a 'Block' object to use in a platform game. So I make a new .as file, name it Block.as, and define the Block class within it like so: package { public class Block { public function Block() { // constructor code } public function run() { } } } I don't want to add the code yet, I just want to ensure that this works. So in my main timeline code, I try to create an instance of the Block object and execute its run method: var block1:Block = new Block(); block1.run(); Every time it gives me this inane error: Scene 1, Layer 'Layer 1', Frame 1, Line 2 1061: Call to a possibly undefined method run through a reference with static type Block. What undefined method!? It's defined RIGHT THERE in Block.as. The class file is even in the same folder and everything. I'm getting REALLY annoyed at how poorly Flash handles such a ridiculously simple project. Does anyone know why Flash hates me?

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• What to call factory-like (java) methods used with immutable objects

  - by StaxMan

  When creating classes for "immutable objects" immutable meaning that state of instances can not be changed; all fields assigned in constructor) in Java (and similar languages), it is sometimes useful to still allow creation of modified instances. That is, using an instance as base, and creating a new instance that differs by just one property value; other values coming from the base instance. To give a simple example, one could have class like: public class Circle { final double x, y; // location final double radius; public Circle(double x, double y, double r) { this.x = x; this.y = y; this.r = r; } // method for creating a new instance, moved in x-axis by specified amount public Circle withOffset(double deltaX) { return new Circle(x+deltaX, y, radius); } } So: what should method "withOffset" be called? (note: NOT what its name ought to be -- but what is this class of methods called). Technically it is kind of a factory method, but somehow that does not seem quite right to me, since often factories are just given basic properties (and are either static methods, or are not members of the result type but factory type). So I am guessing there should be a better term for such methods. Since these methods can be used to implement "fluent interface", maybe they could be "fluent factory methods"? Better suggestions? EDIT: as suggested by one of answers, java.math.BigDecimal is a good example with its 'add', 'subtract' (etc) methods. Also: I noticed that there's this question (by Jon Skeet no less) that is sort of related (although it asks about specific name for method)

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• Constructing a WeakReference<T> throws COMException

  - by ChaseMedallion

  The following code: IDisposable d = ... new WeakReference<IDisposable>(d); Has started throwing the following exception on SOME machines. What could cause this? System.Runtime.InteropServices.COMException: Unspecified error (Exception from HRESULT: 0x80004005 (E_FAIL)) EDIT: the machines that experience the error are running Windows Server 2008 R2. Windows Server 2012 and desktop machines running windows 7 work fine. (this is true, but I now think a different issue is the relevant difference... see below). EDIT: as an additional note, this occurred right after updating our codebase to Entity Framework 6.1.1.-beta1. In the above code, The IDisposable is a class which wraps an EF DbContext. EDIT: why the votes to close? EDIT: the stack trace of the failure ends at the WeakReference<T> constructor called in the above code: at System.WeakReference`1..ctor(T target, Boolean trackResurrection) // from here on down it's code we wrote/simple LINQ. None of this code has changed recently; // we just upgraded to EF6 and saw this failure start happening at Core.Data.EntityFrameworkDataContext.RegisterDependentDisposable(IDisposable child) at Core.Data.ServiceFactory.GetConstructorParameter[TService](Type parameterType) at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext() at System.Linq.Buffer`1..ctor(IEnumerable`1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at Core.Data.ServiceFactory.CreateService[TService]() at MVC controller action method EDIT: it turns out that the machines having issues with this were running AppDynamics. Uninstalling that seems to have removed the issue.

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• Scala path dependent return type from parameter

  - by Rich Oliver

  In the following code using 2.10.0M3 in Eclipse plugin 2.1.0 for 2.10M3. I'm using the default setting which is targeting JVM 1.5 class GeomBase[T <: DTypes] { abstract class NewObjs { def newHex(gridR: GridBase, coodI: Cood): gridR.HexRT } class GridBase { selfGrid => type HexRT = HexG with T#HexTr def uniformRect (init: NewObjs) { val hexCood = Cood(2 ,2) val hex: HexRT = init.newHex(selfGrid, hexCood)// won't compile } } } Error message: Description Resource Path Location Type type mismatch; found: GeomBase.this.GridBase#HexG with T#HexTr required: GridBase.this.HexRT (which expands to) GridBase.this.HexG with T#HexTr GeomBase.scala Why does the compiler think the method returns the type projection GridBase#HexG when it should be this specific instance of GridBase? Edit transferred to a simpler code class in responce to comments now getting a different error message. package rStrat class TestClass { abstract class NewObjs { def newHex(gridR: GridBase): gridR.HexG } class GridBase { selfGrid => def uniformRect (init: NewObjs) { val hex: HexG = init.newHex(this) //error here } class HexG { val test12 = 5 } } } . Error line 11:Description Resource Path Location Type type mismatch; found : gridR.HexG required: GridBase.this.HexG possible cause: missing arguments for method or constructor TestClass.scala /SStrat/src/rStrat line 11 Scala Problem Update I've switched to 2.10.0M4 and updated the plug-in to the M4 version on a fresh version of Eclipse and switched to JVM 1.6 (and 1.7) but the problems are unchanged.

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• How can I get swig to wrap a linked list-type structure?

  - by bk

  Here's what I take to be a pretty standard header for a list. Because the struct points to itself, we need this two-part declaration. Call it listicle.h: typedef struct _listicle listicle; struct _listicle{ int i; listicle *next; }; I'm trying to get swig to wrap this, so that the Python user can make use of the listicle struct. Here's what I have in listicle.i right now: %module listicle %{ #include "listicle.h" %} %include listicle.h %rename(listicle) _listicle; %extend listicle { listicle() {return malloc (sizeof(listicle));} } As you can tell by my being here asking, it doesn't work. All the various combinations I've tried each fail in their own special way. [This one: %extend defined for an undeclared class listicle. Change it to %extend _listicle (and fix the constructor) and loading in Python gives type object '_listicle' has no attribute '_listicle_swigregister'. And so on.] Suggestions?

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• C# XNA: What can cause SpriteBatch.End() to throw a NRE?

  - by Rosarch

  I don't understand what I'm doing wrong here: public void Draw(GameTime gameTime) // in ScreenManager { SpriteBatch.Begin(SpriteBlendMode.AlphaBlend); for (int i = 0; i < Screens.Count; i++) { if (Screens[i].State == Screen.ScreenState.HIDDEN) continue; Screens[i].Draw(gameTime); } SpriteBatch.End(); // null ref exception } SpriteBatch itself is not null. Some more context: public class MasterEngine : Microsoft.Xna.Framework.Game { public MasterEngine() { graphicsDeviceManager = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); // ... spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); screenManager = new ScreenManager(assets, gameEngine, graphicsDeviceManager.GraphicsDevice, spriteBatch); } //... protected override void Draw(GameTime gameTime) { screenManager.Draw(gameTime); // calls the problematic method base.Draw(gameTime); } } Am I failing to initialize something properly? UPDATE: As an experiment, I tried this to the constructor of MasterEngine: spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); spriteBatch.Begin(); spriteBatch.DrawString(assets.GetAsset<SpriteFont>("calibri"), "ftw", new Vector2(), Color.White); spriteBatch.End(); This does not cause a NRE. hmm.... UPDATE 2: This does cause an NRE: protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.End(); // boned here //screenManager.Draw(gameTime); base.Draw(gameTime); }

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• Nesting arbitrary objects in Java

  - by user1502381

  I am having trouble solving a particular problem in Java (which I did not find by search). I do not know how to create a nested lists of objects - with a different type of object/primitive type at the end. For example: *Note: only an example. I am actually doing this below with something other than Employee, but it serves as simple example. I have an array of an object Employee. It contains information on the Employee. public class Employee { int age int salary int yearsWorking public Employee () { // constructor... } // Accessors } What I need to do is organize the Employees by quantiles/percentiles. I have done so by the following: import org.apache.commons.math.stat.descriptive.rank.Percentile; public class EmployeeSort { public void main(String args[]) { Percentile p = new Percentile(); Employee[] employeeArray = new Employee(100); // filled employeeArray double[] ageArray new double[100]; // filled ageArray with ages from employeeArray int q = 25; // Percentile cutoff for (int i = 1; i*q < 100; i++) { // assign percentile cutoff to some array to contain the values } } } Now, the problem I have is that I need to organize the Employees first by the percentiles of age, then percentiles of yearsWorking, and finally by percentiles of salary. My Java knowledge is inadequate right now to solve this problem, but the project I was handed was in Java. I am primarily a python guy, so this problem would have been a lot easier in that language. No such luck.

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• this is my first time asking here, I wanted to create a linked list while sorting it thanks

  - by user2738718

  package practise; public class Node { // node contains data and next public int data; public Node next; //constructor public Node (int data, Node next){ this.data = data; this.next = next; } //list insert method public void insert(Node list, int s){ //case 1 if only one element in the list if(list.next == null && list.data > s) { Node T = new Node(s,list); } else if(list.next == null && list.data < s) { Node T = new Node(s,null); list.next = T; } //case 2 if more than 1 element in the list // 3 elements present I set prev to null and curr to list then performed while loop if(list.next.next != null) { Node curr = list; Node prev = null; while(curr != null) { prev = curr; curr = curr.next; if(curr.data > s && prev.data < s){ Node T = new Node(s,curr); prev.next = T; } } // case 3 at the end checks for the data if(prev.data < s){ Node T = new Node(s,null); prev.next = T; } } } } // this is a hw problem, i created the insert method so i can check and place it in the correct order so my list is sorted This is how far I got, please correct me if I am wrong, I keep inserting node in the main method, Node root = new Node(); and root.insert() to add.

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• Organising UI code in .NET forms

  - by sb3700

  Hi I'm someone who has taught myself programming, and haven't had any formal training in .NET programming. A while back, I started C# in order to develop a GUI program to control sensors, and the project has blossomed. I was just wondering how best to organise the code, particularly UI code, in my forms. My forms currently are a mess, or at least seem a mess to me. I have a constructor which initialises all the parameters and creates events. I have a giant State property, which updates the Enabled state of all my form control as users progress through the application (ie: disconnected, connected, setup, scanning) controlled by a States enum. I have 3-10 private variables accessed through properties, some of which have side-effects in changing the values of form elements. I have a lot of "UpdateXXX" functions to handle UI elements that depend on other UI elements - ie: if a sensor is changed, then change the baud rate drop down list. They are separated into regions I have a lot of events calling these Update functions I have a background worker which does all the scanning and analysis. My problem is this seems like a mess, particularly the State property, and is getting unmaintainable. Also, my application logic code and UI code are in the same file and to some degree, intermingled which seems wrong and means I need to do a lot of scrolling to find what I need. How do you structure your .net forms? Thanks

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• useer degined Copy ctor, and copy-ctors further down the chain - compiler bug ? programers brainbug

  - by J.Colmsee

  Hi. i have a little problem, and I am not sure if it's a compiler bug, or stupidity on my side. I have this struct : struct BulletFXData { int time_next_fx_counter; int next_fx_steps; Particle particles[2];//this is the interesting one ParticleManager::ParticleId particle_id[2]; }; The member "Particle particles[2]" has a self-made kind of smart-ptr in it (resource-counted texture-class). this smart-pointer has a default constructor, that initializes to the ptr to 0 (but that is not important) I also have another struct, containing the BulletFXData struct : struct BulletFX { BulletFXData data; BulletFXRenderFunPtr render_fun_ptr; BulletFXUpdateFunPtr update_fun_ptr; BulletFXExplosionFunPtr explode_fun_ptr; BulletFXLifetimeOverFunPtr lifetime_over_fun_ptr; BulletFX( BulletFXData data, BulletFXRenderFunPtr render_fun_ptr, BulletFXUpdateFunPtr update_fun_ptr, BulletFXExplosionFunPtr explode_fun_ptr, BulletFXLifetimeOverFunPtr lifetime_over_fun_ptr) :data(data), render_fun_ptr(render_fun_ptr), update_fun_ptr(update_fun_ptr), explode_fun_ptr(explode_fun_ptr), lifetime_over_fun_ptr(lifetime_over_fun_ptr) { } /* //USER DEFINED copy-ctor. if it's defined things go crazy BulletFX(const BulletFX& rhs) :data(data),//this line of code seems to do a plain memory-copy without calling the right ctors render_fun_ptr(render_fun_ptr), update_fun_ptr(update_fun_ptr), explode_fun_ptr(explode_fun_ptr), lifetime_over_fun_ptr(lifetime_over_fun_ptr) { } */ }; If i use the user-defined copy-ctor my smart-pointer class goes crazy, and it seems that calling the CopyCtor / assignment operator aren't called as they should. So - does this all make sense ? it seems as if my own copy-ctor of struct BulletFX should do exactly what the compiler-generated would, but it seems to forget to call the right constructors down the chain. compiler bug ? me being stupid ? Sorry about the big code, some small example could have illustrated too. but often you guys ask for the real code, so well - here it is :D

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• What are the original reasons for ToString() in Java and .NET?

  - by d.

  I've used ToString() modestly in the past and I've found it very useful in many circumstances. However, my usage of this method would hardly justify to put this method in none other than System.Object. My wild guess is that, at some point during the work carried out and meetings held to come up with the initial design of the .NET framework, it was decided that it was necessary - or at least extremely useful - to include a ToString() method that would be implemented by everything in the .NET framework. Does anyone know what the exact reasons were? Am I missing a ton of situations where ToString() proves useful enough as to be part of System.Object? What were the original reasons for ToString()? Thanks a lot! PS - Again: I'm not questioning the method or implying that it's not useful, I'm just curious to know what makes it SO useful as to be placed in System.Object. Side note - Imagine this: AnyDotNetNativeClass someInitialObject = new AnyDotNetNativeClass([some constructor parameters]); AnyDotNetNativeClass initialObjectFullCopy = AnyDotNetNativeClass.FromString(someInitialObject.ToString()); Wouldn't this be cool? EDIT(1): (A) - Based on some answers, it seems that .NET languages inherited this from Java. So, I'm adding "Java" to the subject and to the tags as well. If someone knows the reasons why this was implemented in Java then please shed some light! (B) - Static hypothetical FromString vs Serialization: sure, but that's quite a different story, right?

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• How to process events chain.

  - by theblackcascade

  I need to process this chain using one LoadXML method and one urlLoader object: ResourceLoader.Instance.LoadXML("Config.xml"); ResourceLoader.Instance.LoadXML("GraphicsSet.xml"); Loader starts loading after first frameFunc iteration (why?) I want it to start immediatly.(optional) And it starts loading only "GraphicsSet.xml" Loader class LoadXml method: public function LoadXML(URL:String):XML { urlLoader.addEventListener(Event.COMPLETE,XmlLoadCompleteListener); urlLoader.load(new URLRequest(URL)); return xml; } private function XmlLoadCompleteListener(e:Event):void { var xml:XML = new XML(e.target.data); trace(xml); trace(xml.name()); if(xml.name() == "Config") XMLParser.Instance.GameSetup(xml); else if(xml.name() == "GraphicsSet") XMLParser.Instance.GraphicsPoolSetup(xml); } Here is main: public function Main() { Mouse.hide(); this.addChild(Game.Instance); this.addEventListener(Event.ENTER_FRAME,Game.Instance.Loop); } And on adding a Game.Instance to the rendering queue in game constuctor i start initialize method: public function Game():void { trace("Constructor"); if(_instance) throw new Error("Use Instance Field"); Initialize(); } its code is: private function Initialize():void { trace("initialization"); ResourceLoader.Instance.LoadXML("Config.xml"); ResourceLoader.Instance.LoadXML("GraphicsSet.xml"); } Thanks.

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• convert a textview, including those contents off the screen, to bitmap

  - by user623318

  Hi, I want to save(export) contents of MyView, which extends TextView, into a bitmap. I followed the code: [this][1]. It works fine when the size of the text is small. But when there are lots of texts, and some of the content is out of the screen, what I got is only what showed in the screen. Then I add a "layout" in my code: private class MyView extends TextView{ public MyView(Context context) { super(context); // TODO Auto-generated constructor stub } public Bitmap export(){ Layout l = getLayout(); int width = l.getWidth() + getPaddingLeft() + getPaddingRight(); int height = l.getHeight() + getPaddingTop() + getPaddingBottom(); Bitmap viewBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(viewBitmap); setCursorVisible(false); layout(0, 0, width, height); draw(canvas); setCursorVisible(true); return viewBitmap; } } Now the strange thing happened: The first time I invoke "export"(I use an option key to do that), I got contents only on the screen. When I invoke "export" again, I got complete contents, including those out of the screen. Why? How to "export" a view, including contents cannot be showed on the screen? Thank you! [1]: http://www.techjini.com/blog/2010/02/10/quicktip-how-to-convert-a-view-to-an-image-android/ this

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• Vector does reallocation on every push_back

  - by Amrish

  IDE - Visual Studio 2008, Visual C++ I have a custom class Class1 with a copy constructor to it. I also have a vector Data is inserted using the following code Class1* objClass1; vector<Class1> vClass1; for(int i=0;i<1000;i++) { objClass1 = new Class1(); vClass1.push_back(*objClass1); delete objClass1; } Now on every insert, the vector gets re-allocated and all the existing contents are copied to new locations. For example, if the vector has 5 elements and if I insert the 6th one, the previous 5 elements along with the new one gets copied to a new location (I figured it out by adding log statements in the copy constructors.) On using reserve(), this however does not happen as expected! I have the following questions Is it mandatory to always use the reserve statement? Does vector does a reallocation every time I do a push_back; or does it happen because I am debugging?

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• Any problems with this C++ const reference accessor interface idiom?

  - by mskfisher

  I was converting a struct to a class so I could enforce a setter interface for my variables. I did not want to change all of the instances where the variable was read, though. So I converted this: struct foo_t { int x; float y; }; to this: class foo_t { int _x; float _y; public: foot_t() : x(_x), y(_y) { set(0, 0.0); } const int &x; const float &y; set(int x, float y) { _x = x; _y = y; } }; I'm interested in this because it seems to model C#'s idea of public read-only properties. Compiles fine, and I haven't seen any problems yet. Besides the boilerplate of associating the const references in the constructor, what are the downsides to this method? Any strange aliasing issues? Why haven't I seen this idiom before?

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• Can a custom MFC window/dialog be a class template instantiation?

  - by John

  There's a bunch of special macros that MFC uses when creating dialogs, and in my quick tests I'm getting weird errors trying to compile a template dialog class. Is this likely to be a big pain to achieve? Here's what I tried: MyDlg.h template <class W> class CMyDlg : public CDialog { typedef CDialog super; DECLARE_DYNAMIC(CMyDlg <W>) public: CMyDlg (CWnd* pParent); // standard constructor virtual ~CMyDlg (); // Dialog Data enum { IDD = IDD_MYDLG }; protected: virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support DECLARE_MESSAGE_MAP() private: W *m_pWidget; //W will always be a CDialog }; IMPLEMENT_DYNAMIC(CMyDlg<W>, super) <------------------- template <class W> CMyDlg<W>::CMyDlg(CWnd* pParent) : super(CMyDlg::IDD, pParent) { m_pWidget = new W(this); } I get a whole bunch of errors but main one appears to be: error C2955: 'CMyDlg' : use of class template requires template argument list I tried using some specialised template versions of macros but it doesn't help much, other errors change but this one remains. Note my code is all in one file, since C++ templates don't like .h/.cpp like normal. I'm assuming someone must have done this in the past, possibly creating custom versions of macros, but I can't find it by searching, since 'template' has other meanings.

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• Random number generation in MVC applications

  - by SlimShaggy

  What is the correct way of generating random numbers in an ASP.NET MVC application if I need exactly one number per request? According to MSDN, in order to get randomness of sufficient quality, it is necessary to generate multiple numbers using a single System.Random object, created once. Since a new instance of a controller class is created for each request in MVC, I cannot use a private field initialized in the controller's constructor for the Random object. So in what part of the MVC app should I create and store the Random object? Currently I store it in a static field of the controller class and lazily initialize it in the action method that uses it: public class HomeController : Controller { ... private static Random random; ... public ActionResult Download() { ... if (random == null) random = new Random(); ... } } Since the "random" field can be accessed by multiple instances of the controller class, is it possible for its value to become corrupted if two instances attempt to initialize it simultaneously? And one more question: I know that the lifetime of statics is the lifetime of the application, but in case of an MVC app what is it? Is it from IIS startup till IIS shutdown?

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• Help C++ifying this C style code.

  - by Flamewires

  Hey I'm used to developing in C and I would like to use C++ in a project. Can anyone give me an example of how I would translate this C-style code into C++ code. I know it should compile in a c++ complier but I'm talking using c++ techniques(I.e. classes, RAII) typedef struct Solution Solution; struct Solution { double x[30]; int itt_found; double value; }; Solution *NewSolution() { Solution *S = (Solution *)malloc(sizeof(Solution)); for (int i=0;<=30;i++) { S-x[i] = 0; } S-itt_found = -1; return S; } void FreeSolution(Solution *S) { if (S != NULL) free(S); } int main() { Solution *S = NewSolution(); S-value = eval(S-x);// evals is another function that returns a double S-itt_found = 0; FreeSolution(S); return EXIT_SUCCESS; } Ideally I would like to be able to so something like this in main, but I'm not sure exactly how to create the class, i've read a lot of stuff but incorporating it all together correctly seems a little hard atm. Solution S(30);//constructor that takes as an argument the size of the double array S.eval();//a method that would run eval on S.x[] and store result in S.value cout << S.value << endl; Ask if you need more info, thanks.

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• Is excessive DataTable usage bad?

  - by Justin R.

  I was recently asked to assist another team in building an ASP .NET website. They already have a significant amount of code written -- I was specifically asked build a few individual pages for the site. While exploring the code for the rest of the site, the amount of DataTables being constructed jumped out at me. Being a relatively new in the field, I've never worked on an application that utilizes a database as much as this site does, so I'm not sure how common this is. It seems that whenever data is queried from our database, the results are stored in a DataTable. This DataTable is then usually passed around by itself, or it's passed to a constructor. Classes that are initialized with a DataTable always assign the DataTable to a private/protected field, however only a few of these classes implement IDisposable. In fact, in the thousands of lines of code that I've browsed so far, I have yet to see the Dispose method called on a DataTable. If anything, this doesn't seem to be good OOP. Is this something that I should worry about? Or am I just paying more attention to detail than I should? Assuming you're most experienced developers than I am, how would you feel or react if someone who was just assigned to help you with your site approached you about this "problem"?

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• Designing a chain of states

  - by devoured elysium

  I want to model a kind of FSM(Finite State Machine). I have a sequence of states (let's say, from StateA to StateZ). This sequence is called a Chain and is implemented internally as a List. I will add states by the order I want them to run. My purpose is to be able to make a sequence of actions in my computer (for example, mouse clicks). (I know this has been done a zillion times). So a state is defined as a: boolean Precondition() <- Checks to see if for this state, some condition is true. For example, if I want to click in the Record button of a program, in this method I would check if the program's process is running or not. If it is, go to the next state in the chain list, otherwise, go to what was defined as the fail state (generally is the first state of them all). IState GetNextState() <- Returns the next state to evaluate. If Precondition() was sucessful, it should yield the next state in the chain otherwise it should yield the fail state. Run() Simply checks the Precondition() and sets the internal data so GetNextState() works as expected. So, a naive approach to this would be something like this: Chain chain = new Chain(); //chain.AddState(new State(Precondition, FailState, NextState) <- Method structure chain.AddState(new State(new WinampIsOpenCondition(), null, new <problem here, I want to referr to a state that still wasn't defined!>); The big problem is that I want to make a reference to a State that at this point still wasn't defined. I could circumvent the problem by using strings when refrering to states and using an internal hashtable, but isn't there a clearer alternative? I could just pass only the pre-condition and failure states in the constructor, having the chain just before execution put in each state the correct next state in a public property but that seems kind of awkward.

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• Help dealing with data dependency between two registration forms

  - by franko75

  I have a tricky issue here with a registration of both a user and his/her pet. Both the user and the pet are treated as separate entities and both require separate registration forms. However, the user's pet has to be linked to the user via a foreign key in the database. The process is basically that when a new user joins the site, firstly they register their pet, then they register themselves. The reason for this order is to check their pet's eligibility for the site (there are some criteria to be met) first, instead of getting the user to sign up only to then find out their pet is ineligible. It is this ordering of the form submissions which is causing me a bit of a headache, as follows... The site is being developed with an MVC framework, and the User registration process is managed via a method in a User_form controller, while the pet registration process is managed via a method in the Pet_form controller. The pet registration form happens first, and the pet data can be saved without the owner_id at this stage, with the user id possibly being added (e.g by retrieving pet's id from session) following user registration. However, doing it this way could potentially result in redundant data, where pet records would be created in the database, but if the user doesn't actually register themselves too, then the pets will be ownerless records in the DB. Other option is to serialize the new pet's data at the pet registration stage, don't save it to the DB until the user fills out their registration form. Once the user is created, i can pass serialised data AND the owner_id to a method in the Pet Model which can update the DB. However, I also need to set the newly created $pet to $this-pet which I then access for a sequence of other related forms. Should I just set the session variable in the model method? Then in the Pet controller constructor, do a check for pet stored in session, if yes, assign to $this-pet... If this makes any sense to anybody and you have some advice, i'd be grateful to hear it!

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• EF4 + STE: Reattaching via a WCF Service? Using a new objectcontext each and every time?

  - by Martin

  Hi there, I am planning to use WCF (not ria) in conjunction with Entity Framework 4 and STE (Self tracking entitites). If i understnad this correctly my WCF should return an entity or collection of entities (using LIST for example and not IQueryable) to the client (in my case silverlight) The client then can change the entity or update it. At this point i believe it is self tracking???? This is where i sort of get a bit confused as there are a lot of reported problems with STEs not tracking.. Anyway... Then to update i just need to send back the entity to my WCF service on another method to do the update. I should be creating a new OBJECTCONTEXT everytime? In every method? If i am creaitng a new objectcontext everytime in everymethod on my WCF then don't i need to re-attach the STE to the objectcontext? So basically this alone wouldn't work?? using(var ctx = new MyContext()) { ctx.Orders.ApplyChanges(order); ctx.SaveChanges(); } Or should i be creating the object context once in the constructor of the WCF service so that 1 call and every additional call using the same wcf instance uses the same objectcontext? I could create and destroy the wcf service in each method call from the client - hence creating in effect a new objectcontext each time. I understand that it isn't a good idea to keep the objectcontext alive for very long. Any insight or information would be gratefully appreciated thanks

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