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  • From WinForm to WPF: A Quick Reference Guide

    Michael Sorens provides a handy wallchart to help migration between WinForm / WPF, VS 2008 / 2010, and .NET 3.5 / 4.0. this can be downloaded for free from the speech-bubble at the head of the article. He also describes the current weaknesses in WPF, and the most obvious differences between the two.

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  • From WinForm to WPF: A Quick Reference Guide

    Michael Sorens provides a handy wallchart to help migration between WinForm / WPF, VS 2008 / 2010, and .NET 3.5 / 4.0. this can be downloaded for free from the speech-bubble at the head of the article. He also describes the current weaknesses in WPF, and the most obvious differences between the two....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • C#/.NET Little Wonders: The Nullable static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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  • Interfaces Reference Model available

    - by ACShorten
    With the implementation of an Oracle Utilities Application Framework based products, you can implement other Oracle technologies to augment your solution. There is a whitepaper available now to outline all the technology integrations possible with various versions of the Oracle Utilities Application Framework. The whitepaper outlines the possible integrations and implementations of other Oracle technologies to address customer requirements in association with Oracle Utilities Application Framework based products. The whitepaper covers a vast range of products including: Oracle Fusion Middleware Oracle SOA Suite Oracle Identity Management Suite Oracle ExaData and Oracle ExaLogic Oracle VM Data Options including Real Application Clustering, Real Application Testing, Data Guard/Active Data Guard, Compression, Partitioning, Database Vault, Audit Vault etc.. The whitepaper contains a summary of the integration solution possibilities, links to further information including product specific interfaces. The whitepaper is available from My Oracle Support at KB Id: 1506855.1

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  • Why do iterators in Python raise an exception?

    - by NullUserException
    Here's the syntax for iterators in Java (somewhat similar syntax in C#): Iterator it = sequence.iterator(); while (it.hasNext()) { System.out.println(it.next()); } Which makes sense. Here's the equivalent syntax in Python: it = iter(sequence) while True: try: value = it.next() except StopIteration: break print(value) I thought Exceptions were supposed to be used only in, well, exceptional circumstances. Why does Python use exceptions to stop iteration?

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  • Help, i cant reference my vars!

    - by SystemNetworks
    I have a sub-class(let's call it sub) and it contains all the function of an object in my game. In my main class(Let's call it main), i connect my sub to main. (Example sub Code: s = new sub(); Then I put my sub function at the update method. Code: s.myFunc(); Becuase in my sub, i have booleans, integers, float and more. The problem is that I don't want to connect my main class to use my main's int, booleans and others. If i connect it, it will have a stack overflow. This is what I put in my sub: Code: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Input; import org.newdawn.slick.state.StateBasedGame; public class Armory { package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Input; import org.newdawn.slick.state.StateBasedGame; public class Store { public Integer wood; public Float probePositionX; public Float probePositionY; public Boolean StoreOn; public Boolean darkBought; public Integer money; public Integer darkEnergy; public Integer lifeLeft; public Integer powerLeft; public void darkStores(GameContainer gc, StateBasedGame sbg, GameContainer gc2) { Input input1 = gc.getInput(); //Player need wood to enter(200) If not there will be an error. if(wood>=200) { //Enter Store! if(input1.isKeyDown(Input.KEY_Q)) { //Player must be in this cord! if((probePositionX>393 && probePositionX<555) && (probePositionY< 271 && probePositionY>171)) { //The Store is On StoreOn=true; } } } } } In my main (update function) I put: Code: s.darkBought = darkBought; s.darkEnergy = darkEnergy; s.lifeLeft = lifeLeft; s.money = money; s.powerLeft = powerLeft; s.probePositionX = probePositionX; s.probePositionY = probePositionY; s.StoreOn = StoreOn; s.wood = wood; s.darkStores(gc, sbg, gc); The problem is when I go to the place, and I press q, nothing shows up. It should show another image. Is there anything wrong???

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  • Are nullable types preferable to magic numbers?

    - by Matt H
    I have been having a little bit of a debate with a coworker lately. We are specifically using C#, but this could apply to any language with nullable types. Say for example you have a value that represents a maximum. However, this maximum value is optional. I argue that a nullable number would be preferable. My coworker favors the use of zero, citing precedent. Granted, things like network sockets have often used zero to represent an unlimited timeout. If I were to write code dealing with sockets today, I would personally use a nullable value, since I feel it would better represent the fact that there is NO timeout. Which representation is better? Both require a condition checking for the value meaning "none", but I believe that a nullable type conveys the intent a little bit better.

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  • Session and Cache are By Reference

    Recently a colleague remarked that if he got a List of some type out of the ASP.NET Cache, and changed an item, the Cache item would also change.That is correct. Session (InProc) , Cache and Application all return "live" references. A good writeup on this can be found by friend and fellow MVP Rick Strahl here:http://www.west-wind.com/Weblog/posts/1214.aspxIf you do not want this behavior, you need to either delete the Session / Cache / Application object and replace it with what you want later, or...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Is there a Design Pattern for preventing dangling references?

    - by iFreilicht
    I was thinking about a design for custom handles. The thought is to prevent clients from copying around large objects. Now a regular handle class would probably suffice for that, but it doesn't solve the "dangling reference problem"; If a client has multiple handles of the same object and deletes the object via one of them, all the others would be invalid, but not know it, so the client could write or read parts of the memory he shouldn't have access to. Is there a design pattern to prevent this from happening? Two ideas: An observer-like pattern where the destructor of an object would notify all handles. "Handle handles" (does such a thing even exist?). All the handles don't really point to the object, but to another handle. When the object gets destroyed, this "master-handle" invalidates itself and therefore all that point to it.

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  • Missing resource exception when running OIM design console under OEL6u2

    - by user12674042
    If you're trying to run the OIM design console (xlclient.sh) under OEL 6u2 and keep getting this error after entering the credentials: ... Caused by: java.util.MissingResourceException: Can't find oracle.iam.platform.utils.resources.LRB bundle... Make sure your wlfullclient.jar is in the ext folder of the designconsole folder... and yes, the design console runs perfectly well in OEL 6u2.

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  • "PHP: Good Parts"-ish book / reference

    - by julkiewicz
    Before I had my first proper contact with Javascript I read an excellent book "Javascript: The Good Parts" by Douglas Crockford. I was hoping for something similar in case of PHP. My first thought was this book: "PHP: The Good Parts" from O'Reilly However after I read the reviews it seems it totally misses the point. I am looking for a resource that would: concentrate on known shortcommings of PHP, give concrete examples, be as exhaustive as possible I already see that things can go wrong. If you want to close this question: Please consider this, I looked through SO, and Programmers for materials. I obviously found this question: http://stackoverflow.com/questions/90924/what-is-the-best-php-programming-book It's general, mine is specific. Moreover I'm reading the top recommendation "PHP Objects, Patterns, and Practice" right now. I find it insufficient -- it doesn't address the bad practices as much as I would like it to. tl;dr My question is NOT a general PHP book request.

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  • Good practice or service for monitoring unhandled application errors for a small organization

    - by palto
    I'm working with multiple software with varying ways of monitoring for errors. When I make software, I usually send email with the stack trace to admins(usually me). Some customer software is monitored by a team who check that a particular batch run was successfull. Other software might not have any monitoring at all(someone will call when things go wrong horribly). Sending emails is good, except when things start going wrong, my mail gets filled fast. Also I don't want to solve the same problem in code for every software. Is there some relatively cheap and low maintenance software or practice to handle this. I want it to be cheap/low maintenance because usually I work alone or in teams of 5 or smaller. For example it would be great if errors would be aggregated so I don't get 10 000 emails when something unexpected happens... For clarification: By unhandled errors I mean Exceptions that were unhandled by application code that were propagated to Tomcat or Jboss. I don't need help with how to catch those errors. I need help with what to do with them. Is there any cloud application that I could send my errors to? Or some simple server to install? Or some library that can handle errors using configuration files. I use Java if that is any help.

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  • XNA Skinned Model - Keyframe.Bone out of range exception

    - by idlackage
    I'm getting an IndexOutOfRangeException on this line of AnimationPlayer.cs: boneTransforms[keyframe.Bone] = keyframe.Transform; I don't get what it's really referring to. The error happens when keyframe.Bone is 14, but I have no idea what that's supposed to mean. The 14th bone of my model? What would that even be? I read this thread, but nothing there seemed to work. I don't have many bones, stray edges/verts, unassigned verts, unparented/non-root bones, or bones with dots in the name. What else can I be missing? Thank you for any help!

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  • Resolving an App-Relative URL without a Page Object Reference

    - by Damon
    If you've worked with ASP.NET before then you've almost certainly seen an application-relative URL like ~/SomeFolder/SomePage.aspx.  The tilde at the beginning is a stand in for the application path, and it can easily be resolved using the Page object's ResolveUrl method: string url = Page.ResolveUrl("~/SomeFolder/SomePage.aspx"); There are times, however, when you don't have a page object available and you need to resolve an application relative URL.  Assuming you have an HttpContext object available, the following method will accomplish just that: public static string ResolveAppRelativeUrl(string url) {      return url.Replace("~", System.Web.HttpContext.Current.Request.ApplicationPath); } It just replaces the tilde with the application path, which is essentially all the ResolveUrl method does.

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  • Deploying a very simple application

    - by vanna
    I have a very simple working console application written in C++ linked with a light static library. It is just for testing purposes. Now that the coding part is done, I would like to know the process of actually deploying the program. I wrote a very basic CMakeLists.txt that create makefiles or VS projects to build the sources. I also have a program that calls the static library in order to make some google tests. To me, the distribution of this application goes like this : to developpers : the src directory with the CMakeLists.txt file (multi-platform distribution) with a README.txt and an INSTALL.txt to users : the executable and a README.txt git repo : everything mentionned above plus the sources for testing and the gtest external lib A this point : considering the complexity of my application, am I doing it right ? Is there any reference that would formalize this deployment process so I can get better and go further ? Say I would like to add dynamic libraries that can be updated, external libraries like boost : how should I package this to deploy it in a professionnal way ?

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  • Decision for Unchecked Exceptions in Scala

    - by Jatin
    As a java programmer, I have always been critical of Unchecked Exceptions. Mostly programmers use it as an en-route to coding easiness only to create trouble later. Also the programs (though untidy) with checked exceptions are much robust compared to unchecked counterparts. Surprisingly in Scala, there is nothing called Checked Exceptions. All the Java checked and unchecked are unchecked in Scala. What is the motivation behind this decision? For me it opens wide range of problems when using any external code. And if by chance the documentation is poor, it results in KILL.

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  • Null Or Empty Coalescing

    - by Latest Microsoft Blogs
    In my last blog post, I wrote about the proper way to check for empty enumerations and proposed an IsNullOrEmpty method for collections which sparked a lot of discussion. This post covers a similar issue, but from a different angle. A very long time ago Read More......(read more)

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  • How to add an exception to this rewrite rule

    - by codecowboy
    Hi, I need to change this so that one file in wp-admin is not forced through https: # add a trailing slash to /wp-admin RewriteCond %{REQUEST_URI} ^.*/wp-admin$ RewriteRule ^(.+)$ https://%{SERVER_NAME}/$1/ [R=301,L] This forces all requests to /wp-admin through SSL but it is breaking a wordpress plugin which needs to access wp-admin/admin-ajax.php. Is there a way to adjust the rule so that it will allow non encrypted requests to that one file? thanks!

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  • HRESULT E_FAIL Exception! (5 replies)

    Hi, I am trying to generate a powerpoint presentation in C#. It works well on my local machine which is running XP. When I run the application on Windows Server 2003 (our Server) the presentation gives HRESULT E FAIL when I call the following code chart (Microsoft.Office.Interop.Graph.Chart)slide.Shapes.AddOLEObject (GetLeft(i), GetTop(i), GetWidth(i), GetHeight(i), &quot;MSGraph.Chart&quot;, &quot;&quot;, Microsoft....

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  • Session and Cache are By Reference

    Recently a colleague remarked that if he got a List of some type out of the ASP.NET Cache, and changed an item, the Cache item would also change.That is correct. Session (InProc) , Cache and Application all return "live" references. A good writeup on this can be found by friend and fellow MVP Rick Strahl here:http://www.west-wind.com/Weblog/posts/1214.aspxIf you do not want this behavior, you need to either delete the Session / Cache / Application object and replace it with what you want later, or...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Session and Cache are By Reference

    Recently a colleague remarked that if he got a List of some type out of the ASP.NET Cache, and changed an item, the Cache item would also change.That is correct. Session (InProc) , Cache and Application all return "live" references. A good writeup on this can be found by friend and fellow MVP Rick Strahl here:http://www.west-wind.com/Weblog/posts/1214.aspxIf you do not want this behavior, you need to either delete the Session / Cache / Application object and replace it with what you want later, or...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Obtain reference to Parent object during instantiation

    - by GoldBishop
    I have a situation where a custom class is a property of another class. What i need to be able to do, if it is possible at all, is obtain a reverse to the "parent" class (ie the the class that holds the current class as a property). For Instance: Public Class Class1 ... public readonly property Prop11 as Class2 public property Prop12 as String ... End Class Public Class Class2 ... private _par as Class1 private _var21 as string ... Public Sub New(...) me._par = ???? ... End Sub public readonly property Prop21 as string Get return me._par.Prop12 & me._var21 End Get End Property ... End Class Ultimately, i am trying to access other properties within Class1 from Class2 as they do have substance for information from within Class2. There are several other classes within Class1 that provide descriptive information to other classes contained within it as properties but the information is not extensible to all of the classes through Inheritance, as Class1 is being used as a resource bin for the property classes and the application itself. Diagram, lazy design ;): Application <- Class1.Prop12 Application <- Class1.Prop11.Prop21 Question: Is it possible to get a recursion through this design setup?

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