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• Class as first-class object

  - by mrpyo

  Could a class be a first-class object? If yes, how would the implementation look? I mean, how could syntax for dynamically creating new classes look like? EDIT: I mean what example syntax could look like (I'm sorry, English is not my native language), but still I believe this question makes sense - how you give this functionality while keeping language consistent. For example how you create reference for new type. Do you make reference first-class object too and then use something like this: Reference<newType> r = new Reference<newType>(); r.set(value); Well this could get messy so you may just force user to use Object type references for dynamically created classes, but then you loose type-checking. I think creating concise syntax for this is interesting problem which solving could lead to better language design, maybe language which is metalanguage for itself (I wonder if this is possible).

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• Are dynamic languages at disadvantage for agile development?

  - by Gerenuk

  From what I've read agile development often involves refactoring or reverse engineering code into diagrams. Of course there is much more than that, but if we consider the practices that rely on these two methods, are dynamically typed languages at disadvantage? It seem static typing would make refactoring and reverse engineering much easier? Refactoring or (automated) reverse engineering is hard if not impossible in dynamically typed languages? What does real world projects tell about usage of dynamically typed languages for agile methodology?

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• Class DIagram Aggregation

  - by GigaPr

  Hi, i came across this definition Aggregation has two properties: antisymmetry, transitivity What does it mean? thanks

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• C++ class initialisation containing class variable initialization

  - by Phil Hannent

  I noticed some code of a colleague today that initialized class variables in the initialization. However it was causing a warning, he says because of the order they are in. My question is why is it better to do variable initialization where it currently is and not within the curly brackets? DiagramScene::DiagramScene( int slideNo, QRectF screenRect, MainWindow* parent ) : QGraphicsScene( screenRect, parent ), myParent( parent ), slideUndoImageCurrentIndex(-1), nextGroupID(0), m_undoInProgress(false), m_deleteItemOnNextUndo(0) line(0), path(0) { /* Setup default brush for background */ scDetail->bgBrush.setStyle(Qt::SolidPattern); scDetail->bgBrush.setColor(Qt::white); setBackgroundBrush(scDetail->bgBrush); }

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• Check if a class is subclass of another class in Java

  - by craesh

  Hi! I'm playing around with Java's reflection API and trying to handle some fields. Now I'm stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. But how do I check derived classes? E.g. LinkedList as subclass of List. I can't find any isSubclassOf(...) or extends(...) method. Do I need to walk through all getSuperClass() and find my supeclass by my own? Thanks! craesh

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• Static member class - declare class private and class member package-private?

  - by Helper Method

  Consider you have the following class public class OuterClass { ... private static class InnerClass { int foo; int bar; } } I think I've read somewhere (but not the official Java Tutorial) that if I would declare the static member classes attributes private, the compiler had to generate some sort of accessor methods so that the outer class can actually access the static member class's (which is effectively a package-private top level class) attributes. Any ideas on that?

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• C# 4.0 'dynamic' and foreach statement

  - by ControlFlow

  Not long time before I've discovered, that new dynamic keyword doesn't work well with the C#'s foreach statement: using System; sealed class Foo { public struct FooEnumerator { int value; public bool MoveNext() { return true; } public int Current { get { return value++; } } } public FooEnumerator GetEnumerator() { return new FooEnumerator(); } static void Main() { foreach (int x in new Foo()) { Console.WriteLine(x); if (x >= 100) break; } foreach (int x in (dynamic)new Foo()) { // :) Console.WriteLine(x); if (x >= 100) break; } } } I've expected that iterating over the dynamic variable should work completely as if the type of collection variable is known at compile time. I've discovered that the second loop actually is looked like this when is compiled: foreach (object x in (IEnumerable) /* dynamic cast */ (object) new Foo()) { ... } and every access to the x variable results with the dynamic lookup/cast so C# ignores that I've specify the correct x's type in the foreach statement - that was a bit surprising for me... And also, C# compiler completely ignores that collection from dynamically typed variable may implements IEnumerable<T> interface! The full foreach statement behavior is described in the C# 4.0 specification 8.8.4 The foreach statement article. But... It's perfectly possible to implement the same behavior at runtime! It's possible to add an extra CSharpBinderFlags.ForEachCast flag, correct the emmited code to looks like: foreach (int x in (IEnumerable<int>) /* dynamic cast with the CSharpBinderFlags.ForEachCast flag */ (object) new Foo()) { ... } And add some extra logic to CSharpConvertBinder: Wrap IEnumerable collections and IEnumerator's to IEnumerable<T>/IEnumerator<T>. Wrap collections doesn't implementing Ienumerable<T>/IEnumerator<T> to implement this interfaces. So today foreach statement iterates over dynamic completely different from iterating over statically known collection variable and completely ignores the type information, specified by user. All that results with the different iteration behavior (IEnumarble<T>-implementing collections is being iterated as only IEnumerable-implementing) and more than 150x slowdown when iterating over dynamic. Simple fix will results a much better performance: foreach (int x in (IEnumerable<int>) dynamicVariable) { But why I should write code like this? It's very nicely to see that sometimes C# 4.0 dynamic works completely the same if the type will be known at compile-time, but it's very sadly to see that dynamic works completely different where IT CAN works the same as statically typed code. So my question is: why foreach over dynamic works different from foreach over anything else?

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• Converting dynamic to basic disk

  - by Josip Medved

  I converted basic disk to dynamic on my laptop. However, now I cannot install Windows 7 on another partition. I just get message that installing them on dynamic disk is not supported. Is there a way to convert dynamic disk to basic without losing data on already existing partition?

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• VS2012 - How to manually convert .NET Class Library to a Portable Class Library

  - by Igor Milovanovic

  The portable libraries are the  response to the growing profile fragmentation in .NET frameworks. With help of portable libraries you can share code between different runtimes without dreadful #ifdef PLATFORM statements or even worse “Add as Link” source file sharing practices. If you have an existing .net class library which you would like to reference from a different runtime (e.g. you have a .NET Framework 4.5 library which you would like to reference from a Windows Store project), you can either create a new portable class library and move the classes there or edit the existing .csproj file and change the XML directly. The following example shows how to convert a .NET Framework 4.5 library to a Portable Class Library. First Unload the Project and change the following settings in the .csproj file: <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" /> to: <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable \$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" /> and add the following keys to the first property group in order to get visual studio to show the framework picker dialog: <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB}; {FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>   After that you can select the frameworks in the Library Tab of the Portable Library:   As last step, delete any framework references from the library as you have them already referenced via the .NET Portable Subset.     [1] Cross-Platform Development with the .NET Framework - http://msdn.microsoft.com/en-us/library/gg597391.aspx [2] Framework Profiles in .NET: http://nitoprograms.blogspot.de/2012/05/framework-profiles-in-net.html

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• What is common case for @dynamic usage ?

  - by Forrest

  There is previous post about difference of @synthesize and @dynamic. I wanna to know more about dynamic from the perspective of how to use @dynamic usually. Usually we use @dynamic together with NSManagedObject // Movie.h @interface Movie : NSManagedObject { } @property (retain) NSString* title; @end // Movie.m @implementation Movie @dynamic title; @end Actually there are no generated getter/setter during compiler time according to understanding of @dynamic, so it is necessary to implement your own getter/setter. My question is that in this NSManagedObject case, what is the rough implementation of getter/setter in super class NSManagedObject ? Except above case, how many other cases to use @dynamic ? Thanks,

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• jQuery how to add class to a parent div which has a 3rd level child div with a specific class name.

  - by Vikram

  Hello friends I have an issue adding a special class to a couple of my divs. My layout is like this. <div class="container"> <div class="grid-6 push-3 equal" style="height: 999px;"> <div class="block"> <div id="mainbody"> <!-- Body content here --> </div> </div> </div> <div class="grid-2 equal" style="height: 999px;"> <div class="block"> <div id="sidebar-a"> <!-- Sidebar-a content here --> </div> </div> </div> <div class="grid-2 equal" style="height: 999px;"> <div class="block"> <div id="sidebar-b"> <!-- Sidebar-b content here --> </div> </div> </div> <div class="grid-2 equal" style="height: 999px;"> <div class="block"> <div id="sidebar-b"> <!-- Sidebar-c content here --> </div> </div> </div> </div> I want to add a different background color to each of my sidebars via CSS and when I code like: #mainbody { background : #fff; } #sidebar-a { background : #eee; } #sidebar-b { background : #ddd; } #sidebar-c { background : #ccc; } It is applying the background only to that specific class but that specific class is not of equal height. I actually need to apply to this <div class="grid-2 equal" style="height: 999px;"> div. Now the issue is that in this <div class="grid-6 push-3 equal" style="height: 999px;"> and class="grid-2 equal" style="height: 999px;"> the class names grid-6 and grid-2 are generated dynamically by my PHP of 960 Grid System and also the style="height: 999px; is generated by a jQuery script for Equal-Columns. What I want is to add a unique class name like this...... Look for a div with a class of .equal which has a child div with a class of .block and which further has a child div with an ID of sidebar-a. IF TRUE then add a class of .sidebar-a to the maindiv which has a class of .equal So that the result looks like this: <div class="grid-6 equal push-3 mainbody" style="height: 999px;"> <div class="grid-2 equal sidebar-a" style="height: 999px;"> <div class="grid-2 equal sidebar-b" style="height: 999px;"> <div class="grid-2 equal sidebar-c" style="height: 999px;"> Then I'll be able to style it like this: .mainbody { background : #fff; } .sidebar-a { background : #eee; } .sidebar-b { background : #ddd; } .sidebar-c { background : #ccc; } Hence I thought since I am anyway using jQuery in my Template, why not use it to deal with this issue. Please feel free to suggest a better way if you have something else in mind.

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• Why is an anonymous inner class containing nothing generated from this code?

  - by Andrew Westberg

  When run through javac on the cmd line Sun JVM 1.6.0_20, this code produces 6 .class files OuterClass.class OuterClass$1.class OuterClass$InnerClass.class OuterClass$InnerClass2.class OuterClass$InnerClass$InnerInnerClass.class OuterClass$PrivateInnerClass.class When run through JDT in eclipse, it produces only 5 classes. OuterClass.class OuterClass$1.class OuterClass$InnerClass.class OuterClass$InnerClass2.class OuterClass$InnerClass$InnerInnerClass.class OuterClass$PrivateInnerClass.class When decompiled, OuterClass$1.class contains nothing. Where is this extra class coming from and why is it created? package com.test; public class OuterClass { public class InnerClass { public class InnerInnerClass { } } public class InnerClass2 { } //this class should not exist in OuterClass after dummifying private class PrivateInnerClass { private String getString() { return "hello PrivateInnerClass"; } } public String getStringFromPrivateInner() { return new PrivateInnerClass().getString(); } }

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• Dynamic JSON Parsing in .NET with JsonValue

  - by Rick Strahl

  So System.Json has been around for a while in Silverlight, but it's relatively new for the desktop .NET framework and now moving into the lime-light with the pending release of ASP.NET Web API which is bringing a ton of attention to server side JSON usage. The JsonValue, JsonObject and JsonArray objects are going to be pretty useful for Web API applications as they allow you dynamically create and parse JSON values without explicit .NET types to serialize from or into. But even more so I think JsonValue et al. are going to be very useful when consuming JSON APIs from various services. Yes I know C# is strongly typed, why in the world would you want to use dynamic values? So many times I've needed to retrieve a small morsel of information from a large service JSON response and rather than having to map the entire type structure of what that service returns, JsonValue actually allows me to cherry pick and only work with the values I'm interested in, without having to explicitly create everything up front. With JavaScriptSerializer or DataContractJsonSerializer you always need to have a strong type to de-serialize JSON data into. Wouldn't it be nice if no explicit type was required and you could just parse the JSON directly using a very easy to use object syntax? That's exactly what JsonValue, JsonObject and JsonArray accomplish using a JSON parser and some sweet use of dynamic sauce to make it easy to access in code. Creating JSON on the fly with JsonValue Let's start with creating JSON on the fly. It's super easy to create a dynamic object structure. JsonValue uses the dynamic  keyword extensively to make it intuitive to create object structures and turn them into JSON via dynamic object syntax. Here's an example of creating a music album structure with child songs using JsonValue:[TestMethod] public void JsonValueOutputTest() { // strong type instance var jsonObject = new JsonObject(); // dynamic expando instance you can add properties to dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; album.Artist = "AC/DC"; album.YearReleased = 1977; album.Songs = new JsonArray() as dynamic; dynamic song = new JsonObject(); song.SongName = "Dirty Deeds Done Dirt Cheap"; song.SongLength = "4:11"; album.Songs.Add(song); song = new JsonObject(); song.SongName = "Love at First Feel"; song.SongLength = "3:10"; album.Songs.Add(song); Console.WriteLine(album.ToString()); } This produces proper JSON just as you would expect: {"AlbumName":"Dirty Deeds Done Dirt Cheap","Artist":"AC\/DC","YearReleased":1977,"Songs":[{"SongName":"Dirty Deeds Done Dirt Cheap","SongLength":"4:11"},{"SongName":"Love at First Feel","SongLength":"3:10"}]} The important thing about this code is that there's no explicitly type that is used for holding the values to serialize to JSON. I am essentially creating this value structure on the fly by adding properties and then serialize it to JSON. This means this code can be entirely driven at runtime without compile time restraints of structure for the JSON output. Here I use JsonObject() to create a new object and immediately cast it to dynamic. JsonObject() is kind of similar in behavior to ExpandoObject in that it allows you to add properties by simply assigning to them. Internally, JsonValue/JsonObject these values are stored in pseudo collections of key value pairs that are exposed as properties through the DynamicObject functionality in .NET. The syntax gets a little tedious only if you need to create child objects or arrays that have to be explicitly defined first. Other than that the syntax looks like normal object access sytnax. Always remember though these values are dynamic - which means no Intellisense and no compiler type checking. It's up to you to ensure that the values you create are accessed consistently and without typos in your code. Note that you can also access the JsonValue instance directly and get access to the underlying type. This means you can assign properties by string, which can be useful for fully data driven JSON generation from other structures. Below you can see both styles of access next to each other:// strong type instance var jsonObject = new JsonObject(); // you can explicitly add values here jsonObject.Add("Entered", DateTime.Now); // expando style instance you can just 'use' properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; JsonValue internally stores properties keys and values in collections and you can iterate over them at runtime. You can also manipulate the collections if you need to to get the object structure to look exactly like you want. Again, if you've used ExpandoObject before JsonObject/Value are very similar in the behavior of the structure. Reading JSON strings into JsonValue The JsonValue structure supports importing JSON via the Parse() and Load() methods which can read JSON data from a string or various streams respectively. Essentially JsonValue includes the core JSON parsing to turn a JSON string into a collection of JsonValue objects that can be then referenced using familiar dynamic object syntax. Here's a simple example:[TestMethod] public void JsonValueParsingTest() { var jsonString = @"{""Name"":""Rick"",""Company"":""West Wind"",""Entered"":""2012-03-16T00:03:33.245-10:00""}"; dynamic json = JsonValue.Parse(jsonString); // values require casting string name = json.Name; string company = json.Company; DateTime entered = json.Entered; Assert.AreEqual(name, "Rick"); Assert.AreEqual(company, "West Wind"); } The JSON string represents an object with three properties which is parsed into a JsonValue object and cast to dynamic. Once cast to dynamic I can then go ahead and access the object using familiar object syntax. Note that the actual values - json.Name, json.Company, json.Entered - are actually of type JsonPrimitive and I have to assign them to their appropriate types first before I can do type comparisons. The dynamic properties will automatically cast to the right type expected as long as the compiler can resolve the type of the assignment or usage. The AreEqual() method oesn't as it expects two object instances and comparing json.Company to "West Wind" is comparing two different types (JsonPrimitive to String) which fails. So the intermediary assignment is required to make the test pass. The JSON structure can be much more complex than this simple example. Here's another example of an array of albums serialized to JSON and then parsed through with JsonValue():[TestMethod] public void JsonArrayParsingTest() { var jsonString = @"[ { ""Id"": ""b3ec4e5c"", ""AlbumName"": ""Dirty Deeds Done Dirt Cheap"", ""Artist"": ""AC/DC"", ""YearReleased"": 1977, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/61kTaH-uZBL._AA115_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B00008BXJ4/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B00008BXJ4"", ""Songs"": [ { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Dirty Deeds Done Dirt Cheap"", ""SongLength"": ""4:11"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Love at First Feel"", ""SongLength"": ""3:10"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Big Balls"", ""SongLength"": ""2:38"" } ] }, { ""Id"": ""67280fb8"", ""AlbumName"": ""Echoes, Silence, Patience & Grace"", ""Artist"": ""Foo Fighters"", ""YearReleased"": 2007, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/41mtlesQPVL._SL500_AA280_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B000UFAURI/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000UFAURI"", ""Songs"": [ { ""AlbumId"": ""67280fb8"", ""SongName"": ""The Pretender"", ""SongLength"": ""4:29"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Let it Die"", ""SongLength"": ""4:05"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Erase/Replay"", ""SongLength"": ""4:13"" } ] }, { ""Id"": ""7b919432"", ""AlbumName"": ""End of the Silence"", ""Artist"": ""Henry Rollins Band"", ""YearReleased"": 1992, ""Entered"": ""2012-03-16T00:13:12.2800521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/51FO3rb1tuL._SL160_AA160_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/End-Silence-Rollins-Band/dp/B0000040OX/ref=sr_1_5?ie=UTF8&qid=1302232195&sr=8-5"", ""Songs"": [ { ""AlbumId"": ""7b919432"", ""SongName"": ""Low Self Opinion"", ""SongLength"": ""5:24"" }, { ""AlbumId"": ""7b919432"", ""SongName"": ""Grip"", ""SongLength"": ""4:51"" } ] } ]"; dynamic albums = JsonValue.Parse(jsonString); foreach (dynamic album in albums) { Console.WriteLine(album.AlbumName + " (" + album.YearReleased.ToString() + ")"); foreach (dynamic song in album.Songs) { Console.WriteLine("\t" + song.SongName ); } } Console.WriteLine(albums[0].AlbumName); Console.WriteLine(albums[0].Songs[1].SongName);}   It's pretty sweet how easy it becomes to parse even complex JSON and then just run through the object using object syntax, yet without an explicit type in the mix. In fact it looks and feels a lot like if you were using JavaScript to parse through this data, doesn't it? And that's the point…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  Web Api  JSON   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Class Loading Deadlocks

  - by tomas.nilsson

  Mattis follows up on his previous post with one more expose on Class Loading Deadlocks As I wrote in a previous post, the class loading mechanism in Java is very powerful. There are many advanced techniques you can use, and when used wrongly you can get into all sorts of trouble. But one of the sneakiest deadlocks you can run into when it comes to class loading doesn't require any home made class loaders or anything. All you need is classes depending on each other, and some bad luck. First of all, here are some basic facts about class loading: 1) If a thread needs to use a class that is not yet loaded, it will try to load that class 2) If another thread is already loading the class, the first thread will wait for the other thread to finish the loading 3) During the loading of a class, one thing that happens is that the <clinit method of a class is being run 4) The <clinit method initializes all static fields, and runs any static blocks in the class. Take the following class for example: class Foo { static Bar bar = new Bar(); static { System.out.println("Loading Foo"); } } The first time a thread needs to use the Foo class, the class will be initialized. The <clinit method will run, creating a new Bar object and printing "Loading Foo" But what happens if the Bar object has never been used before either? Well, then we will need to load that class as well, calling the Bar <clinit method as we go. Can you start to see the potential problem here? A hint is in fact #2 above. What if another thread is currently loading class Bar? The thread loading class Foo will have to wait for that thread to finish loading. But what happens if the <clinit method of class Bar tries to initialize a Foo object? That thread will have to wait for the first thread, and there we have the deadlock. Thread one is waiting for thread two to initialize class Bar, thread two is waiting for thread one to initialize class Foo. All that is needed for a class loading deadlock is static cross dependencies between two classes (and a multi threaded environment): class Foo { static Bar b = new Bar(); } class Bar { static Foo f = new Foo(); } If two threads cause these classes to be loaded at exactly the same time, we will have a deadlock. So, how do you avoid this? Well, one way is of course to not have these circular (static) dependencies. On the other hand, it can be very hard to detect these, and sometimes your design may depend on it. What you can do in that case is to make sure that the classes are first loaded single threadedly, for example during an initialization phase of your application. The following program shows this kind of deadlock. To help bad luck on the way, I added a one second sleep in the static block of the classes to trigger the unlucky timing. Notice that if you uncomment the "//Foo f = new Foo();" line in the main method, the class will be loaded single threadedly, and the program will terminate as it should. public class ClassLoadingDeadlock { // Start two threads. The first will instansiate a Foo object, // the second one will instansiate a Bar object. public static void main(String[] arg) { // Uncomment next line to stop the deadlock // Foo f = new Foo(); new Thread(new FooUser()).start(); new Thread(new BarUser()).start(); } } class FooUser implements Runnable { public void run() { System.out.println("FooUser causing class Foo to be loaded"); Foo f = new Foo(); System.out.println("FooUser done"); } } class BarUser implements Runnable { public void run() { System.out.println("BarUser causing class Bar to be loaded"); Bar b = new Bar(); System.out.println("BarUser done"); } } class Foo { static { // We are deadlock prone even without this sleep... // The sleep just makes us more deterministic try { Thread.sleep(1000); } catch(InterruptedException e) {} } static Bar b = new Bar(); } class Bar { static { try { Thread.sleep(1000); } catch(InterruptedException e) {} } static Foo f = new Foo(); }

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• should I extend or create instance of the class

  - by meWantToLearn

  I have two classes Class A and Class B in Class A, i have three methods that perform the save, delete and select operation based upon the object I pass them. in Class B I perform the logic operations, such as modification to the property of the object before being passed to the methods of Class A, My problem is in Class B, should it extend Class A, and call the methods of class A , by parent::methodName or create instance of class A and then call Class A does not includes any property just methods. class A{ public function save($obj){ //code here } public function delete($obj){ //code here } public function select($obj){ //code here } } //Should I extend class A, and call the method by parent::methodName($obj) or create an instance of class A, call the method $instanceOfA-methodName($obj); class B extends A{ public function checkIfHasSaved($obj){ if($obj->saved == 'Yes'){ parent::save($obj); //**should I call the method like this** $instanceOFA = new A(); //**or create instance of class A and call without extending class A** instanceOFA->save($obj); } //other logic operations here } }

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• java class creation dynamically and make it accessible across the network different jvms i.e. serial

  - by inj.rav

  Hi. I have a requirement of creating java classes dynamically and make it accessible different jvms across the network. I tried to use reflection and javassist tool,but nothing worked. Let me explain the scenario we are using Coherence distributed cache. It has a power of doing aggregation/filtering in parallel across the cluster. For example if a class has [dynamic class] has amount variable and getAmount/setAmount methods. Then if we execute COHERENCE queries, it will start process in parallel across the cluster. I tried to create classes at run time by using javassist and reflection. I am able to access it from single JVM, but when I tried to access the same class from other jvm [through coherence cluster]. I am getting exception of class not found [as remote jvm is not having idea of this class].I can over come this by creating same class dynamically on remote jvm also and access the methods. But coherence in built methods/functions are not able to find the class. could some one help me on this matter

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• How to make that the LanguageBinder take precedence over the DynamicBinder

  - by rudimenter

  Hi I Have a class which implement IDynamicMetaObjectProvider I implement the BindGetMember Method from DynamicMetaObject. Now when i Generate a dynamic Object and Access a property every call gets implicit passed through the BindGetMember Method. I want that at first the language Binder get his chance before my code comes in. It is somehow doable with "binder.FallbackGetMember" but i am not sure how the expression has to look like. I call here dynamic com=CommandFactory.GetCommand(); com.testprop; //expected: "test"; but "test2" comes back public class Command : System.Dynamic.IDynamicMetaObjectProvider { public string testprop { get { return "test"; } } public object GetValue(string name) { return "test2"; } System.Dynamic.DynamicMetaObject System.Dynamic.IDynamicMetaObjectProvider.GetMetaObject(System.Linq.Expressions.Expression parameter) { return new MetaCommand(parameter, this); } private class MetaCommand : System.Dynamic.DynamicMetaObject { public MetaCommand(Expression expression, Command value) : base(expression, System.Dynamic.BindingRestrictions.Empty, value) { } public override System.Dynamic.DynamicMetaObject BindGetMember(System.Dynamic.GetMemberBinder binder) { var self = this.Expression; var bag = (Command)base.Value; Expression target; target = Expression.Call( Expression.Convert(self, typeof(Command)), typeof(Command).GetMethod("GetValue"), Expression.Constant(binder.Name) ); var restrictions = BindingRestrictions .GetInstanceRestriction(self, bag); return new DynamicMetaObject(target, restrictions); } #endregion } }

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• Changing multiple objects with a new class name using Jquery

  - by liquilife

  I'd like to click on a trigger and show a specific image. There are multiple triggers which would show a specific image related to it within a set. There are 4 sets The challenge for me is toggling the other images to hide only in this 'set' when one of these triggers are clicked, as there can only be one image showing at a time in each set. Here is the HTML I've put together thus far: <!-- Thumbnails which can be clicked on to toggle the larger preview image --> <div class="materials"> <a href="javascript:;" id="shirtgrey"><img src="/grey_shirt.png" height="122" width="122" /></a> <a href="javascript:;" id="shirtred"><img src="red_shirt.png" height="122" width="122" /></a> <a href="javascript:;" id="shirtblue"><img src="hblue_shirt.png" height="122" width="122" /></a> <a href="javascript:;" id="shirtgreen"><img src="green_shirt.png" height="122" width="122" /></a> </div> <div class="collars"> <a href="javascript:;" id="collargrey"><img src="grey_collar.png" height="122" width="122" /></a> <a href="javascript:;" id="collarred"><img src="red_collar.png" height="122" width="122" /></a> <a href="javascript:;" id="collarblue"><img src="blue_collar.png" height="122" width="122" /></a> <a href="javascript:;" id="collargreen"><img src="green_collar.png" height="122" width="122" /></a> </div> <div class="cuffs"> <a href="javascript:;" id="cuffgrey"><img src="grey_cuff.png" height="122" width="122" /></a> <a href="javascript:;" id="cuffred"><img src="red_cuff.png" height="122" width="122" /></a> <a href="javascript:;" id="cuffblue"><img src="blue_cuff.png" height="122" width="122" /></a> <a href="javascript:;" id="cuffgreen"><img src="/green_cuff.png" height="122" width="122" /></a> </div> <div class="pockets"> <a href="javascript:;" id="pocketgrey"><img src="grey_pocket.png" height="122" width="122" /></a> <a href="javascript:;" id="pocketred"><img src=".png" height="122" width="122" /></a> <a href="javascript:;" id="pocketblue"><img src="blue_pocket.png" height="122" width="122" /></a> <a href="javascript:;" id="pocketgreen"><img src="green_pocket.png" height="122" width="122" /></a> </div> <!-- The larger images where one from each set should be viewable at one time, triggered by the thumb clicked above --> <div class="selectionimg"> <div class="selectShirt"> <img src="grey_shirt.png" height="250" width="250" class="selectShirtGrey show" /> <img src="red_shirt.png" height="250" width="250" class="selectShirtRed hide" /> <img src="blue_shirt.png" height="250" width="250" class="selectShirtBlue hide" /> <img src="green_shirt.png" height="250" width="250" class="selectShirtGreen hide" /> </div> <div class="selectCollar"> <img src="grey_collar.png" height="250" width="250" class="selectCollarGrey show" /> <img src="red_collar.png" height="250" width="250" class="selectCollarRed hide" /> <img src="blue_collar.png" height="250" width="250" class="selectCollarBlue hide" /> <img src="green_collar.png" height="250" width="250" class="selectCollarGreen hide" /> </div> <div class="selectCuff"> <img src="grey_cuff.png" height="250" width="250" class="selectCuffGrey show" /> <img src="red_cuff.png" height="250" width="250" class="selectCuffRed hide" /> <img src="blue_cuff.png" height="250" width="250" class="selectCuffBlue hide" /> <img src="green_cuff.png" height="250" width="250" class="selectCuffGreen hide" /> </div> <div class="selectPocket"> <img src="grey_pocket.png" height="250" width="250" class="selectPocketGrey show" /> <img src="hred_pocket.png" height="250" width="250" class="selectPocketRed hide" /> <img src="blue_pocket.png" height="250" width="250" class="selectPocketBlue hide" /> <img src="green_pocket.png" height="250" width="250" class="selectPocketGreen hide" /> </div> </div> How can jQuery be used to change a class of an image to "show" and ensure that all other images in that same div are set to a class of "hide"? First time posting here. I'm very efficient with HTML and CSS and have a basic understanding of jQuery. I'm learning and this just seems a little bit beyond my abilities at the moment. I hope this all makes sense. Thanks for any help.

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• Getting an object from a 2d array inside of a class

  - by user36324

  I am have a class file that contains two classes, platform and platforms. platform holds the single platform information, and platforms has an 2d array of platforms. Im trying to render all of them in a for loop but it is not working. If you could kindly help me i would greatly appreciate. void Platforms::setUp() { for(int x = 0; x < tilesW; x++){ for(int y = 0; y < tilesH; y++){ Platform tempPlat(x,y,true,renderer,filename,tileSize/scaleW,tileSize/scaleH); platArray[x][y] = tempPlat; } } } void Platforms::show() { for(int x = 0; x < tilesW; x++){ for(int y = 0; y < tilesH; y++){ platArray[x][y].show(renderer,scaleW,scaleH); } } }

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• C# 4.0: casting dynamic to static

  - by Kevin Won

  This is an offshoot question that's related to another I asked here. I'm splitting it off because it's really a sub-question: I'm having difficulties casting an object of type dynamic to another (known) static type. I have an ironPython script that is doing this: import clr clr.AddReference("System") from System import * def GetBclUri(): return Uri("http://google.com") note that it's simply newing up a BCL System.Uri type and returning it. So I know the static type of the returned object. now over in C# land, I'm newing up the script hosting stuff and calling this getter to return the Uri object: dynamic uri = scriptEngine.GetBclUri(); System.Uri u = uri as System.Uri; // casts the dynamic to static fine Works no problem. I now can use the strongly typed Uri object as if it was originally instantiated statically. however.... Now I want to define my own C# class that will be newed up in dynamic-land just like I did with the Uri. My simple C# class: namespace Entity { public class TestPy // stupid simple test class of my own { public string DoSomething(string something) { return something; } } } Now in Python, new up an object of this type and return it: sys.path.append(r'C:..path here...') clr.AddReferenceToFile("entity.dll") import Entity.TestPy def GetTest(): return Entity.TestPy(); // the C# class then in C# call the getter: dynamic test = scriptEngine.GetTest(); Entity.TestPy t = test as Entity.TestPy; // t==null!!! here, the cast does not work. Note that the 'test' object (dynamic) is valid--I can call the DoSomething()--it just won't cast to the known static type string s = test.DoSomething("asdf"); // dynamic object works fine so I'm perplexed. the BCL type System.Uri will cast from a dynamic type to the correct static one, but my own type won't. There's obviously something I'm not getting about this...

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• How to define a static array without a contant size in a constructor of a class? (C++)

  - by Keand64

  I have a class defined as: class Obj { public: int width, height; Obj(int w, int h); } and I need it to contain a static array like so: int presc[width][height]; however, I cannot define within the class, so it it possible to create a pointer to a 2D array (and, out of curiosity, 3, 4, and 5D arrays), have that as a member of the class, and intitalize it in the constructor like: int ar[5][6]; Obj o(5, 6, &ar); If that isn't possible, is there any way to get a static array without a contant size in a class, or am I going to have to use a dynamic array? (Something I don't want to do because I don't plan on ever changing the size of the array after it's created.)

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• What's the best way to implement a dynamic proxy in C#?

  - by gap

  Hi, I've got a need to create a dynamic proxy in C#. I want this class to wrap another class, and take on it's public interface, forwarding calls for those functions: class MyRootClass { public virtual void Foo() { Console.Out.WriteLine("Foo!"); } } interface ISecondaryInterface { void Bar(); } class Wrapper<T> : ISecondaryInterface where T: MyRootClass { public Wrapper(T otherObj) { } public void Bar() { Console.Out.WriteLine("Bar!"); } } Here's how I want to use it: Wrapper<MyRootClass> wrappedObj = new Wrapper<MyRootClass>(new MyRootClass()); wrappedObj.Bar(); wrappedObj.Foo(); to produce: Bar! Foo! Any ideas? What's the easiest way to do this? What's the best way to do this? Thanks so much.

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• C# new class with only single property : derive from base or encapsulate into new ?

  - by Gobol

  I've tried to be descriptive :) It's rather programming-style problem than coding problem in itself. Let's suppose we have : A: public class MyDict { public Dictionary<int,string> dict; // do custom-serialization of "dict" public void SaveToFile(...); // customized deserialization of "dict" public void LoadFromFile(...); } B: public class MyDict : Dictionary<int,string> { } Which option would be better in the matter of programming style ? class B: is to be de/serialized externally. Main problem is : is it better to create new class (which would have only one property - like opt A:) or to create a new class derived - like opt B: ? I don't want any other data processing than adding/removing and de/serializing to stream. Thanks in advance!

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• Static class vs Singleton class in C# [closed]

  - by Floradu88

  Possible Duplicate: What is the difference between all-static-methods and applying a singleton pattern? I need to make a decision for a project I'm working of whether to use static or singleton. After reading an article like this I am inclined to use singleton. What is better to use static class or singleton? Edit 1 : Client Server Desktop Application. Please provide code oriented solutions.

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• polymorphism, inheritance in c# - base class calling overridden method?

  - by Andrew Johns

  This code doesn't work, but hopefully you'll get what I'm trying to achieve here. I've got a Money class, which I've taken from http://www.noticeablydifferent.com/CodeSamples/Money.aspx, and extended it a little to include currency conversion. The implementation for the actual conversion rate could be different in each project, so I decided to move the actual method for retrieving a conversion rate (GetCurrencyConversionRate) into a derived class, but the ConvertTo method contains code that would work for any implementation assuming the derived class has overriden GetCurrencyConversionRate so it made sense to me to keep it in the parent class? So what I'm trying to do is get an instance of SubMoney, and be able to call the .ConvertTo() method, which would in turn use the overriden GetCurrencyConversionRate, and return a new instance of SubMoney. The problem is, I'm not really understanding some concepts of polymorphism and inheritance yet, so not quite sure what I'm trying to do is even possible in the way I think it is, as what is currently happening is that I end up with an Exception where it has used the base GetCurrencyConversionRate method instead of the derived one. Something tells me I need to move the ConvertTo method down to the derived class, but this seems like I'll be duplicating code in multiple implementations, so surely there's a better way? public class Money { public CurrencyConversionRate { get { return GetCurrencyConversionRate(_regionInfo.ISOCurrencySymbol); } } public static decimal GetCurrencyConversionRate(string isoCurrencySymbol) { throw new Exception("Must override this method if you wish to use it."); } public Money ConvertTo(string cultureName) { // convert to base USD first by dividing current amount by it's exchange rate. Money someMoney = this; decimal conversionRate = this.CurrencyConversionRate; decimal convertedUSDAmount = Money.Divide(someMoney, conversionRate).Amount; // now convert to new currency CultureInfo cultureInfo = new CultureInfo(cultureName); RegionInfo regionInfo = new RegionInfo(cultureInfo.LCID); conversionRate = GetCurrencyConversionRate(regionInfo.ISOCurrencySymbol); decimal convertedAmount = convertedUSDAmount * conversionRate; Money convertedMoney = new Money(convertedAmount, cultureName); return convertedMoney; } } public class SubMoney { public SubMoney(decimal amount, string cultureName) : base(amount, cultureName) {} public static new decimal GetCurrencyConversionRate(string isoCurrencySymbol) { // This would get the conversion rate from some web or database source decimal result = new Decimal(2); return result; } }

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