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  • What design pattern will you choose ?

    - by MemoryLeak
    I want to design a class, which contains a procedure to achieve a goal. And it must follow some order to make sure the last method, let's say "ExecuteIt", to behave correctly. in such a case, what design patter will you use ? which can make sure that the user must call the public method according some ordering. If you really don't know what I am saying, then can you share me some concept of choosing a design patter, or what will you consider while design a class?

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  • Software Architecture: Unit of Work design pattern discussion

    - by santiagobasulto
    Hey everybody. According Martin Fowler's Unit of Work description: "Maintains a list of objects that are affected by a business transaction and coordinates the writing out of changes and resolution of concurrency problems." Avoiding very small calls to the database, which ends up being very slow I'm wondering. If we just delimit it to database transaction management, won't prepare statements help with this?

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  • NSString simple pattern matching

    - by SirRatty
    Hi all, Mac OS 10.6, Cocoa project, 10.4 compatibility required. (Please note: my knowledge of regex is quite slight) I need to parse NSStrings, for matching cases where the string contains an embedded tag, where the tag format is: [xxxx] Where xxxx are random characters. e.g. "The quick brown [foxy] fox likes sox". In the above case, I need to grab the string "foxy". (Or nil if no tag is found.) Each string will only have one tag, and the tag can appear anywhere within the string, or may not appear at all. Could someone please help with a way to do that, preferably without having to include another library such as RegexKit. Thank you for any help.

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  • Apply PHP regex replace on a multi-line repeted pattern

    - by Hussain
    Let's say I have this input: I can haz a listz0rs! # 42 # 126 I can haz another list plox? # Hello, world! # Welcome! I want to split it so that each set of hash-started lines becomes a list: I can haz a listz0rs! <ul> <li>42</li> <li>126</li> </ul> I can haz another list plox? <ul> <li>Hello, world!</li> <li>Welcome!</li> </ul> If I run the input against the regex "/(?:(?:(?<=^# )(.*)$)+)/m", I get the following result: Array ( [0] => Array ( [0] => 42 ) Array ( [0] => 126 ) Array ( [0] => Hello, world! ) Array ( [0] => Welcome! ) ) This is fine and dandy, but it doesn't distinguish between the two different lists. I need a way to either make the quantifier return a concatenated string of all the occurrences, or, ideally, an array of all the occurrences. Idealy, this should be my output: Array ( [0] = Array ( [0] = 42 [1] = 126 ) Array ( [0] = Hello, world! [1] = Welcome! ) ) Is there any way of achieving this, and if not, is there a close alternative? Thanks in advance!

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  • Regex and Pattern Matching in Scala

    - by Bruce Ferguson
    I am not strong in regex, and pretty new to Scala. I would like to be able to find a match between the first letter of a word, and one of the letters in a group such as "ABC". In pseudocode, this might look something like: case Process(word) => word.firstLetter match { case([a-c][A-C]) => case _ => } } but I don't know how to grab the first letter in Scala instead of Java, how to express the regular expression properly, nor if it's possible to do this within a case class. Any suggestions? Thanks in advance. Bruce

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  • F# pattern matching when mixing DU's and other values

    - by Roger Alsing
    What would be the most effective way to express the following code? match cond.EvalBool() with | true -> match body.Eval() with | :? ControlFlowModifier as e -> match e with | Break(scope) -> e :> obj //Break is a DU element of ControlFlowModifier | _ -> next() //other members of CFM should call next() | _ -> next() //all other values should call next() | false -> null cond.EvalBool returns a boolean result where false should return null and true should either run the entire block again (its wrapped in a func called next) or if the special value of break is found, then the loop should exit and return the break value. Is there any way to compress that block of code to something smaller?

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  • Apply PHP regex replace on a multi-line repeated pattern

    - by Hussain
    Let's say I have this input: I can haz a listz0rs! # 42 # 126 I can haz another list plox? # Hello, world! # Welcome! I want to split it so that each set of hash-started lines becomes a list: I can haz a listz0rs! <ul> <li>42</li> <li>126</li> </ul> I can haz another list plox? <ul> <li>Hello, world!</li> <li>Welcome!</li> </ul> If I run the input against the regex "/(?:(?:(?<=^# )(.*)$)+)/m", I get the following result: Array ( [0] => Array ( [0] => 42 ) [1] => Array ( [0] => 126 ) [2] => Array ( [0] => Hello, world! ) [3] => Array ( [0] => Welcome! ) ) This is fine and dandy, but it doesn't distinguish between the two different lists. I need a way to either make the quantifier return a concatenated string of all the occurrences, or, ideally, an array of all the occurrences. Ideally, this should be my output: Array ( [0] => Array ( [0] => 42 [1] => 126 ) [1] => Array ( [0] => Hello, world! [1] => Welcome! ) ) Is there any way of achieving this, and if not, is there a close alternative? Thanks in advance!

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  • Problem updating through LINQtoSQL in MVC application using StructureMap, Repository Pattern and UoW

    - by matt
    I have an ASP MVC application using LINQ to SQL for data access. I am trying to use the Repository and Unit of Work patterns, with a service layer consuming the repositories and unit of work. I am experiencing a problem when attempting to perform updates on a particular repository. My application architecture is as follows: My service class: public class MyService { private IRepositoryA _RepositoryA; private IRepositoryB _RepositoryB; private IUnitOfWork _unitOfWork; public MyService(IRepositoryA ARepositoryA, IRepositoryB ARepositoryB, IUnitOfWork AUnitOfWork) { _unitOfWork = AUnitOfWork; _RepositoryA = ARepositoryA; _RepositoryB = ARepositoryB; } public PerformActionOnObject(Guid AID) { MyObject obj = _RepositoryA.GetRecords() .WithID(AID); obj.SomeProperty = "Changed to new value"; _RepositoryA.UpdateRecord(obj); _unitOfWork.Save(); } } Repository interface: public interface IRepositoryA { IQueryable<MyObject> GetRecords(); UpdateRecord(MyObject obj); } Repository LINQtoSQL implementation: public class LINQtoSQLRepositoryA : IRepositoryA { private MyDataContext _DBContext; public LINQtoSQLRepositoryA(IUnitOfWork AUnitOfWork) { _DBConext = AUnitOfWork as MyDataContext; } public IQueryable<MyObject> GetRecords() { return from records in _DBContext.MyTable select new MyObject { ID = records.ID, SomeProperty = records.SomeProperty } } public bool UpdateRecord(MyObject AObj) { MyTableRecord record = (from u in _DB.MyTable where u.ID == AObj.ID select u).SingleOrDefault(); if (record == null) { return false; } record.SomeProperty = AObj.SomePropery; return true; } } Unit of work interface: public interface IUnitOfWork { void Save(); } Unit of work implemented in data context extension. public partial class MyDataContext : DataContext, IUnitOfWork { public void Save() { SubmitChanges(); } } StructureMap registry: public class DataServiceRegistry : Registry { public DataServiceRegistry() { // Unit of work For<IUnitOfWork>() .HttpContextScoped() .TheDefault.Is.ConstructedBy(() => new MyDataContext()); // RepositoryA For<IRepositoryA>() .Singleton() .Use<LINQtoSQLRepositoryA>(); // RepositoryB For<IRepositoryB>() .Singleton() .Use<LINQtoSQLRepositoryB>(); } } My problem is that when I call PerformActionOnObject on my service object, the update never fires any SQL. I think this is because the datacontext in the UnitofWork object is different to the one in RepositoryA where the data is changed. So when the service calls Save() on it's IUnitOfWork, the underlying datacontext does not have any updated data so no update SQL is fired. Is there something I've done wrong in the StrutureMap registry setup? Or is there a more fundamental problem with the design? Many thanks.

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  • Complex pattern replacement using PHP preg_replace function ignoring quoted strings

    - by Saiful
    Consider the following string: this is a STRING WHERE some keywords ARE available. 'i need TO format the KEYWORDS from the STRING' In the above string keywords are STRING and WHERE Now i need to get an output as follows: this is a <b>STRING</b> <b>WHERE</b> some keywords ARE available. 'i need TO format the KEYWORDS from the STRING' So that the html output will be like: this is a STRING WHERE some keywords ARE available. 'i need TO format the KEYWORDS from the STRING' Note that the keywords within a quoted ('...') string will be ignored. in the above example i ignored the STRING keyword within the quoted string. Please give a modified version of the following PHP script so that I can have my desired result as above : $patterns = array('/STRING/','/WHERE/'); $replaces = array('<b>STRING</b>', '<b>WHERE</b>'); $string = "this is a STRING WHERE some keywords ARE available. 'i need TO format the KEYWORDS from the STRING'"; preg_replace($patterns, $replaces, $string);

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  • How do I ensure my abstract class's function can only operate on extenders of the same type as the c

    - by incrediman
    For example, let's say this is my abstract class: abstract class A{ int x; int y; void foo(A fooMe); } ...and B and C are two classes which extend A. What I want is for B to only be able to call foo() on other Bs, and for C to only be able to call foo() on other Cs. But I want this to be out of the hands of the programmer who's extending my A class - that is, I want a way to ensure this functionality within As code alone. What can I do? (If possible) I'd like to avoid any hack or generics solution that's too messy - I still want foo to be able to be called like this, for example: B b=new B(); B bb=new B(); bb.foo(b);

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  • java - check if string ends with certain pattern

    - by The Learner
    I have string like: This.is.a.great.place.too.work. (or) This/is/a/great/place/too/work/ than my java program should give me that the sentence is valid and it has "work". if i Have : This.is.a.great.place.too.work.hahahha (or) This/is/a/great/place/too/work/hahahah Should not give me that there is a work in the sentance. so I am looking at java strings to find a word at the end of the sentance having . (or),(or)/ before it. How can I achieve that

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  • Best Practice, objects design ASP.NET MVC

    - by DoomStone
    Hello Stackoverflow I have a code design question that have been torbeling me for a while, you see I’m doing a refactoring of my website Cosplay Denmark, a site where cospalyers can upload images of them self in their costumes. The original site was done in php, Zend MVC, but my refactoring is being done in ASP.NET MVC 2. If you take the site http://www.cosplaydanmark.dk/Costumes/ (You can switch to English in the left column (Sprog)) Here you see a list of all the anime’s we have on the site with images, we show the name, how many different characters and how many images there are under this anime. http://www.cosplaydanmark.dk/Costumes/Bleach If you click on an anime will you get a list of characters within the given anime which we have images in, here do we show the character name, how many galleries and how many images. http://www.cosplaydanmark.dk/Costumes/Bleach/Ichigo_Kurosaki/ If you click on the character name, will you get a list of the galleries under the given character in the given anime. Here we have some information about the gallery, such as image count. http://www.cosplaydanmark.dk/Costumes/Bleach/Ichigo_Kurosaki/Admi/ Should you click the gallery do you get a list of the images in the gallery. My database look like this at the moment. As you can might imagine there are a lot of different query’s to create the site, on the first site I need to do a select on the on the “animes” table and for each result, I need to do a count select on characters and galleries. My plan to create this will be one of the following Where the IList, would be a lazy load list. But I can’t decide what would be the best solution for this would be, also if there is a better way of doing this. My priority is to have good performance with a minimum lose of features and code upkeep. I’m using a service pattern with a linq to sql repository. My design is not absolute, I’m willing to change it if it could increase performance :D I hope that I have describe my question good enough for you to understand what I mean, but ask away if there are anything I have missed.

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  • Using Lazy<T> and abstract wrapper class to lazy-load complex system parameters

    - by DigiMortal
    .NET Framework 4.0 introduced new class called Lazy<T> and I wrote blog post about it: .Net Framework 4.0: Using System.Lazy<T>. One thing is annoying for me – we have to keep lazy loaded value and its value loader as separate things. In this posting I will introduce you my Lazy<T> wrapper for complex to get system parameters that uses template method to keep lazy value loader in parameter class. Problem with original implementation Here’s the sample code that shows you how Lazy<T> is usually used. This is just sample code, don’t focus on the fact that this is dummy console application. class Program {     static void Main(string[] args)     {         var temperature = new Lazy<int>(LoadMinimalTemperature);           Console.WriteLine("Minimal room temperature: " + temperature.Value);         Console.ReadLine();     }       protected static int LoadMinimalTemperature()     {         var returnValue = 0;           // Do complex stuff here           return true;     } } The problem is that our class with many lazy loaded properties will grow messy if it has all value loading code inside it. This code may be complex for more than one parameter and in this case it is better to use separate class for this parameter. Defining base class for parameters As a first step I will define base class for all lazy-loaded parameters. This class is wrapper around Lazy<T> and it also offers one template method that parameter classes have to override to provide loaded data. public abstract class LazyParameter<T> {     private Lazy<T> _lazyParam;       public LazyParameter()     {         _lazyParam = new Lazy<T>(Load);     }       protected abstract T Load();       public T Value     {         get { return _lazyParam.Value; }     } } It is also possible to extend Lazy<T> but I don’t prefer to do it as Lazy<T> has six constructors we have to take care of. Also I don’t like to expose Lazy<T> public interface to users of my parameter classes. Creating parameter class Now it’s time to create our first parameter class. Notice how few stuff we have in this class besides overridden Load() method. public class MinimalRoomTemperature : LazyParameter<int> {     protected override int Load()     {         var returnValue = 0;           // Do complex stuff here           return returnValue;     } } Using parameter class is simple. Here’s my test code. class Program {     static void Main(string[] args)     {         var parameter = new MinimalRoomTemperature();         Console.WriteLine("Minimal room temperature: " + parameter.Value);         Console.ReadLine();     } } Conclusion Lazy<T> is useful class that you usually don’t want to use outside from API-s. I like this class but I don’t like when people are using this class directly in application code. In this posting I showed you how to use Lazy<T> with wrapper class to get complex parameter loading code out from classes that use this parameter. We ended up with generic base class for parameters that you can also use as base for other similar classes (you have to find better name to base class in this case).

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  • Pure virtual or abstract, what's in a name?

    - by Steven Jeuris
    While discussing a question about virtual functions on Stack Overflow, I wondered whether there was any official naming for pure (abstract) and non-pure virtual functions. I always relied on wikipedia for my information, which states that pure and non-pure virtual functions are the general term. Unfortunately, the article doesn't back it up with a origin or references. To quote Jon Skeet's answer to my reply that pure and non-pure are the general term used: @Steven: Hmm... possibly, but I've only ever seen it in the context of C++ before. I suspect anyone talking about them is likely to have a C++ background :) Did the terms originate from C++, or were they first defined or implemented in a earlier language, and are they the 'official' scientific terms?

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  • Absent Code attribute in method that is not native or abstract

    - by kerry
    I got the following, quite puzzling error today when running a unit test: java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/servlet/http/Cookie A google search found this post, which explains that it is caused by having an interface in the classpath, and not an actual implementation. In this case it’s the java-ee interface. To fix this I added the jetty servlet api implementation to my pom: jetty javax.servlet test Piece of cake. I have run in to this before, so I figured I would capture the fix here in case I run in to it again.

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  • Does my use of the strategy pattern violate the fundamental MVC pattern in iOS?

    - by Goodsquirrel
    I'm about to use the 'strategy' pattern in my iOS app, but feel like my approach violates the somehow fundamental MVC pattern. My app is displaying visual "stories", and a Story consists (i.e. has @properties) of one Photo and one or more VisualEvent objects to represent e.g. animated circles or moving arrows on the photo. Each VisualEvent object therefore has a eventType @property, that might be e.g. kEventTypeCircle or kEventTypeArrow. All events have things in common, like a startTime @property, but differ in the way they are being drawn on the StoryPlayerView. Currently I'm trying to follow the MVC pattern and have a StoryPlayer object (my controller) that knows about both the model objects (like Story and all kinds of visual events) and the view object StoryPlayerView. To chose the right drawing code for each of the different visual event types, my StoryPlayer is using a switch statement. @implementation StoryPlayer // (...) - (void)showVisualEvent:(VisualEvent *)event onStoryPlayerView:storyPlayerView { switch (event.eventType) { case kEventTypeCircle: [self showCircleEvent:event onStoryPlayerView:storyPlayerView]; break; case kEventTypeArrow: [self showArrowDrawingEvent:event onStoryPlayerView:storyPlayerView]; break; // (...) } But switch statements for type checking are bad design, aren't they? According to Uncle Bob they lead to tight coupling and can and should almost always be replaced by polymorphism. Having read about the "Strategy"-Pattern in Head First Design Patterns, I felt this was a great way to get rid of my switch statement. So I changed the design like this: All specialized visual event types are now subclasses of an abstract VisualEvent class that has a showOnStoryPlayerView: method. @interface VisualEvent : NSObject - (void)showOnStoryPlayerView:(StoryPlayerView *)storyPlayerView; // abstract Each and every concrete subclass implements a concrete specialized version of this drawing behavior method. @implementation CircleVisualEvent - (void)showOnStoryPlayerView:(StoryPlayerView *)storyPlayerView { [storyPlayerView drawCircleAtPoint:self.position color:self.color lineWidth:self.lineWidth radius:self.radius]; } The StoryPlayer now simply calls the same method on all types of events. @implementation StoryPlayer - (void)showVisualEvent:(VisualEvent *)event onStoryPlayerView:storyPlayerView { [event showOnStoryPlayerView:storyPlayerView]; } The result seems to be great: I got rid of the switch statement, and if I ever have to add new types of VisualEvents in the future, I simply create new subclasses of VisualEvent. And I won't have to change anything in StoryPlayer. But of cause this approach violates the MVC pattern since now my model has to know about and depend on my view! Now my controller talks to my model and my model talks to the view calling methods on StoryPlayerView like drawCircleAtPoint:color:lineWidth:radius:. But this kind of calls should be controller code not model code, right?? Seems to me like I made things worse. I'm confused! Am I completely missing the point of the strategy pattern? Is there a better way to get rid of the switch statement without breaking model-view separation?

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  • Abstract Data Type and Data Structure

    - by mark075
    It's quite difficult for me to understand these terms. I searched on google and read a little on Wikipedia but I'm still not sure. I've determined so far that: Abstract Data Type is a definition of new type, describes its properties and operations. Data Structure is an implementation of ADT. Many ADT can be implemented as the same Data Structure. If I think right, array as ADT means a collection of elements and as Data Structure, how it's stored in a memory. Stack is ADT with push, pop operations, but can we say about stack data structure if I mean I used stack implemented as an array in my algorithm? And why heap isn't ADT? It can be implemented as tree or an array.

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  • How abstract should you get with BDD

    - by Newton
    I was writing some tests in Gherkin (using Cucumber/Specflow). I was wondering how abstract should I get with my tests. In order to not make this open-ended, which of the following statements is better for BDD: Given I am logged in with email [email protected] and password 12345 When I do something Then something happens as opposed to Given I am logged in as the Administrator When I do something Then something happens The reason I am confused is because 1 is more based on the behaviour (filing in email and password) and 2 is easier to process and write the tests.

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  • Who should map physical keys to abstract keys?

    - by Paul Manta
    How do you bridge the gap between the library's low-level event system and your engine's high-level event system? (I'm not necessarily talking about key events, but also about quit events.) At the top level of my event system, I send out KeyPressedEvents, KeyRelesedEvents and others of this kind. These high-level events only contain the abstract values of the keys (they don't say that Space way pressed, but that the JumpKey was pressed, for example). Whose responsibility should it be to map the "JumpKey" to an actual key on the keyboard?

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  • Upcoming EBS Webcasts for June, July, August 2012

    - by user793553
    See the following upcoming webcasts for June, July and August 2012. Flag Doc ID 740966.1 as a favourite, to keep up to date with latest advisor schedule. Additionally, see Doc ID 740964.1 for access to all archived advisor webcasts Oracle E-Business Suite Oracle E-Business Suite Title Date Summary None at this time.     EBS Agile Title Date Summary None at this time.     EBS Applications Technologies Group (ATG) Title Date Summary EBS – OAM Tuning and Monitoring EMEA July 10, 2012 Abstract EBS – OAM Tuning and Monitoring US July 11, 2012 Abstract Workflow Analyzer Followup EMEA July 24, 2012 Abstract Workflow Analyzer Followup US July 25, 2012 Abstract EBS CRM & Industries Title Date Summary None at this time.     EBS Financials Title Date Summary EBS Fixed Assets: Achieve Success Using Proactive Tools For Fixed Assets Support July 10, 2012 Abstract Overview and Flow of Oracle Project Resource Management July 17, 2012 Abstract Leveraging My Oracle Support To Increase Knowledge July 30, 2012 Abstract EBS HCM (HRMS) Title Date Summary Oracle Time and Labor (OTL) Rollback Functionality Session 1 July 25, 2012 Abstract Oracle Time and Labor (OTL) Rollback Functionality Session 2 July 25, 2012 Abstract EBS Manufacturing Title Date Summary Using Personalization in Oracle eAM June 21, 2012 Abstract OM Guided Resolutions - Finding Known Resolutions Easily July 17, 2012 Abstract Material Move Orders Flow July 25, 2012 Abstract Diagnosing Signal 11 Issues In ASCP Planning August 9, 2012 Abstract Interface Trip Stop - Best Practices and Debugging August 21, 2012 Abstract EBS Procurement Title Date Summary Punchout in iProcurement June 26, 2012 Abstract

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  • Abstract skill/talent system implementation

    - by kiliki
    I've been making small 2D games for about 3 years now (XNA and more recently LWJGL/Slick2D). My latest idea would involve some form of "talent tree" system in a real time game. I've been wracking my brain but can't think of a structure to hold a talent. Something like "Your melee attack is an instant kill if behind the target" I'd like to come up with an abstract object rather than putting random conditionals into other methods. I've solved some relatively complex problems before but I don't even know where to begin with this one. Any help would be appreciated - Java, pseudocode or general concepts are all great.

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  • The Dispose Pattern (and FxCop warnings)

    - by Scott Dorman
    [This is actually a response to Bill’s blog post, but since it isn’t possible to leave this as a comment on his blog it’s a post here.] There are many different ways to implement the Dispose pattern correctly. Some are (in my opinion) better than others. In Bill’s blog post he presents a particular pattern, which is an excerpt from his book (Effective C#). The issue centers around the fact that a reader took the code sample presented in the book and ran FxCop (Code Analysis) on it, which generated a warning: “Ensure that base.Dispose() is always called.” The “lesson learned” that Bill presents is that “tools are there to help us, not control us.” While I completely agree with the belief that tools are there to help us, I think it’s important to understand why FxCop is raising this particular warning. The code presented in Bill’s book looks like: // Have its own disposed flag.private bool disposed = false;protected override void Dispose(bool isDisposing){ // Don't dispose more than once. if (disposed) return; if (isDisposing) { // TODO: free managed resources here. } // TODO: free unmanaged resources here. // Let the base class free its resources. // Base class is responsible for calling // GC.SuppressFinalize( ) base.Dispose(isDisposing); // Set derived class disposed flag: disposed = true;} This code does follow all of the guidelines for implementing the Dispose pattern. In this case, it’s presumably part of a larger example showing how to implement the pattern as part of a base class. The reason FxCop is warning you about this code is the first if statement in the Dispose method, which will cause the method to exit if disposed is true. The problem here is that there is the possibility that if the disposed flag is true, the call to base.Dispose() will never be executed. As Bill points out, it is possible for some other code elsewhere in the class to set this flag. He states that this is an “unlikely occurrence.” While that is probably true, it can be a potentially dangerous assumption to make and is one that can be easily corrected. By changing the code slightly you can remove this assumption and correct the FxCop violation. private bool disposed = false;protected override void Dispose(bool disposing){ if (!disposed) { if (disposing) { // Dispose managed resources. } // Dispose unmanaged resources. disposed = true; } base.Dispose(disposing);} Using this implementation allows the call to base.Dispose() to always occur, which ensures that the the disposal chain is always properly followed. Technorati Tags: .NET,C#,Dispose Pattern

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