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  • Why doesn't every class in the .Net framework have a corresponding interface?

    - by Thorsten Lorenz
    Since I started to develop in a test/behavior driven style, I appreciated the ability to mock out every dependency. Since mocking frameworks like Moq work best when told to mock an interface, I now implement an interface for almost every class I create b/c most likely I will have to mock it out in a test eventually. Well, and programming to an interface is good practice, anyways. At times, my classes take dependencies on .Net classes (e.g. FileSystemWatcher, DispatcherTimer). It would be great in that case to have an interface, so I could depend on an IDispatcherTimer instead, to be able to pass it a mock and simulate its behavior to see if my system under test reacts correctly. Unfortunately both of above mentioned classes do not implement such interfaces, so I have to resort to creating adapters, that do nothing else but inherit from the original class and conform to an interface, that I then can use. Here is such an adapter for the DispatcherTimer and the corresponding interface: using System; using System.Windows.Threading; public interface IDispatcherTimer { #region Events event EventHandler Tick; #endregion #region Properties Dispatcher Dispatcher { get; } TimeSpan Interval { get; set; } bool IsEnabled { get; set; } object Tag { get; set; } #endregion #region Public Methods void Start(); void Stop(); #endregion } /// <summary> /// Adapts the DispatcherTimer class to implement the <see cref="IDispatcherTimer"/> interface. /// </summary> public class DispatcherTimerAdapter : DispatcherTimer, IDispatcherTimer { } Although this is not the end of the world, I wonder, why the .Net developers didn't take the minute to make their classes implement these interfaces from the get go. It puzzles me especially since now there is a big push for good practices from inside Microsoft. Does anyone have any (maybe inside) information why this contradiction exists?

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  • How to register assemblies using Windsor in ASP.NET MVC

    - by oz
    This is how my project looks: TestMvc (my web project) has a reference to the DomainModel.Core assembly where my interfaces and business objects reside. The class that implements the interfaces in DomainModel.Core is in a different assembly called DomainModel.SqlRepository; the reason behind it is that if I just want to create a repository for Oracle I just have to deploy the new dll, change the web.config and be done with it. When I build the solution, if I look at the \bin folder of my TestMvc project, there is no reference to the DomainModel.SqlRepository, which makes sense because it's not being reference anywhere. Problem arises when my windsor controller factory tries to resolve that assembly, since it's not on the \bin directory. So is there a way to point windsor to a specific location, without adding a reference to that assembly? My web.config looks like this: <component id="UserService" service="TestMvc.DomainModel.Core.Interface, TestMvc.DomainModel.Core" type="TestMvc.DomainModel.SqlRepository.Class, TestMvc.DomainModel.SqlRepository" lifestyle="PerWebRequest" /> There's many ways around this, like copying the dll as part of the build, add the reference to the project so it will get copied to the \bin folder or install it on the GAC and add an assembly reference in the web.config. I guess my question is specific to Windsor, to see if I can give the location of my assembly and it will resolve it.

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  • Can the Diamond Problem be really solved?

    - by Mecki
    A typical problem in OO programming is the diamond problem. I have parent class A with two sub-classes B and C. A has an abstract method, B and C implement it. Now I have a sub-class D, that inherits of B and C. The diamond problem is now, what implementation shall D use, the one of B or the one of C? People claim Java knows no diamond problem. I can only have multiple inheritance with interfaces and since they have no implementation, I have no diamond problem. Is this really true? I don't think so. See below: [removed vehicle example] Is a diamond problem always the cause of bad class design and something neither programmer nor compiler needs to solve, because it shouldn't exist in the first place? Update: Maybe my example was poorly chosen. See this image Of course you can make Person virtual in C++ and thus you will only have one instance of person in memory, but the real problem persists IMHO. How would you implement getDepartment() for GradTeachingFellow? Consider, he might be student in one department and teach in another one. So you can either return one department or the other one; there is no perfect solution to the problem and the fact that no implementation might be inherited (e.g. Student and Teacher could both be interfaces) doesn't seem to solve the problem to me.

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  • Design pattern to use instead of multiple inheritance

    - by mizipzor
    Coming from a C++ background, Im used to multiple inheritance. I like the feeling of a shotgun squarely aimed at my foot. Nowadays, I work more in C# and Java, where you can only inherit one baseclass but implement any number of interfaces (did I get the terminology right?). For example, lets consider two classes that implement a common interface but different (yet required) baseclasses: public class TypeA : CustomButtonUserControl, IMagician { public void DoMagic() { // ... } } public class TypeB : CustomTextUserControl, IMagician { public void DoMagic() { // ... } } Both classes are UserControls so I cant substitute the base class. Both needs to implement the DoMagic function. My problem now is that both implementations of the function are identical. And I hate copy-and-paste code. The (possible) solutions: I naturally want TypeA and TypeB to share a common baseclass, where I can write that identical function definition just once. However, due to having the limit of just one baseclass, I cant find a place along the hierarchy where it fits. One could also try to implement a sort of composite pattern. Putting the DoMagic function in a separate helper class, but the function here needs (and modifies) quite a lot of internal variables/fields. Sending them all as (reference) parameters would just look bad. My gut tells me that the adapter pattern could have a place here, some class to convert between the two when necessery. But it also feels hacky. I tagged this with language-agnostic since it applies to all languages that use this one-baseclass-many-interfaces approach. Also, please point out if I seem to have misunderstood any of the patterns I named. In C++ I would just make a class with the private fields, that function implementation and put it in the inheritance list. Whats the proper approach in C#/Java and the like?

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  • Interface and partial classes

    - by Tomek Tarczynski
    According to rule SA1201 in StyleCop elements in class must appear in correct order. The order is following: Fields Constructors Finalizers (Destructors) Delegates Events Enums Interfaces Properties Indexers Methods Structs Classes Everything is ok, except of Interfaces part, because Interface can contain mehtods, events, properties etc... If we want to be strict about this rule then we won't have all members of Interface in one place which is often very useful. According to StyleCop help this problem can be solved by spliting class into partial classes. Example: /// <summary> /// Represents a customer of the system. /// </summary> public partial class Customer { // Contains the main functionality of the class. } /// <content> /// Implements the ICollection class. /// </content> public partial class Customer : ICollection { public int Count { get { return this.count; } } public bool IsSynchronized { get { return false; } } public object SyncRoot { get { return null; } } public void CopyTo(Array array, int index) { throw new NotImplementedException(); } } Are there any other good solutions to this problem?

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  • Why don't file type filters work properly with nsIFilePicker on Mac OSX?

    - by Eric Strom
    I am running a chrome app in firefox (started with -app) with the following code to open a filepicker: var nsIFilePicker = Components.interfaces.nsIFilePicker; var fp = Components.classes["@mozilla.org/filepicker;1"] .createInstance(nsIFilePicker); fp.init(window, "Select Files", nsIFilePicker.modeOpenMultiple); fp.appendFilter("video", "*.mov; *.mpg; *.mpeg; *.avi; *.flv; *.m4v; *.mp4"); fp.appendFilter("all", "*.*"); var res = fp.show(); if (res == nsIFilePicker.returnCancel) return; var files = fp.files; var paths = []; while (files.hasMoreElements()) { var arg = files.getNext().QueryInterface( Components.interfaces.nsILocalFile ).path; paths.push(arg); } Everything seems to work fine on Windows, and the file picker itself works on OSX, but the dropdown menu to select between file types only displays in Windows. The first filter (video in this case) is in effect, but the dropdown to select the other type never shows. Is there something extra that is needed to get this working on OSX? I have tried the latest firefox (3.6) and an older one (3.0.13) and both don't show the file type dropdown on OSX.

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  • RSA example that do not use NoPadding

    - by Tom Brito
    Where can I find a RSA encrypt example that does not use "NoPadding"? --update Better: how to make this code run correctly without throw the "too much data for RSA block" exception? import java.math.BigInteger; import java.security.KeyFactory; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; /** * Basic RSA example. */ public class TestRSA { public static void main(String[] args) throws Exception { byte[] input = new byte[100]; Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC"); KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC"); // create the keys RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger("d46f473a2d746537de2056ae3092c451", 16), new BigInteger("11", 16)); RSAPrivateKeySpec privKeySpec = new RSAPrivateKeySpec(new BigInteger( "d46f473a2d746537de2056ae3092c451", 16), new BigInteger("57791d5430d593164082036ad8b29fb1", 16)); RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec); RSAPrivateKey privKey = (RSAPrivateKey) keyFactory.generatePrivate(privKeySpec); // encryption step cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherText = cipher.doFinal(input); // decryption step cipher.init(Cipher.DECRYPT_MODE, privKey); byte[] plainText = cipher.doFinal(cipherText); } }

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  • JDBC/OSGi and how to dynamically load drivers without explicitly stating dependencies in the bundle?

    - by Chris
    Hi, This is a biggie. I have a well-structured yet monolithic code base that has a primitive modular architecture (all modules implement interfaces yet share the same classpath). I realize the folly of this approach and the problems it represents when I go to deploy on application servers that may have different conflicting versions of my library. I'm dependent on around 30 jars right now and am mid-way though bnding them up. Now some of my modules are easy to declare the versioned dependencies of, such as my networking components. They statically reference classes within the JRE and other BNDded libraries but my JDBC related components instantiate via Class.forName(...) and can use one of any number of drivers. I am breaking everything up into OSGi bundles by service area. My core classes/interfaces. Reporting related components. Database access related components (via JDBC). etc.... I wish for my code to be able to still be used without OSGi via single jar file with all my dependencies and without OSGi at all (via JARJAR) and also to be modular via the OSGi meta-data and granular bundles with dependency information. How do I configure my bundle and my code so that it can dynamically utilize any driver on the classpath and/or within the OSGi container environment (Felix/Equinox/etc.)? Is there a run-time method to detect if I am running in an OSGi container that is compatible across containers (Felix/Equinox/etc.) ? Do I need to use a different class loading mechanism if I am in a OSGi container? Am I required to import OSGi classes into my project to be able to load an at-bundle-time-unknown JDBC driver via my database module? I also have a second method of obtaining a driver (via JNDI, which is only really applicable when running in an app server), do I need to change my JNDI access code for OSGi-aware app servers?

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  • Libtool versioning of a library that depends on other libraries.

    - by Artyom
    Hello, I have a framework that uses Boost and CgiCC in the core application and in its interface. How should I version the library binary interface (a.k.a. libtool -version-info)? I have no problems tracking the changes in library itself when I make various changes. As it is clear for me how should I version. But... Both Boost and CgiCC libraries do not provide any backward compatible API/ABI and my library may be linked with quite arbitrary versions Boost and CgiCC so I can't provide any promise about the interfaces, so I can't really specify -version-info because even the same library compiled against different versions of Boost and CgiCC would not be compatible. So... What should I do? How should I version library? I know that I should not depend on Boost and CgiCC interfaces in first place, but this is what I get so far for existing stable version. This issue is addressed in next major release but I still have and want to maintain current release as it is very valuable.

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  • How to restrict access to a class's data based on state?

    - by Marcus Swope
    In an ETL application I am working on, we have three basic processes: Validate and parse an XML file of customer information from a third party Match values received in the file to values in our system Load customer data in our system The issue here is that we may need to display the customer information from any or all of the above states to an internal user and there is data in our customer class that will never be populated before the values have been matched in our system (step 2). For this reason, I would like to have the values not even be available to be accessed when the customer is in this state, and I would like to have to avoid some repeated logic everywhere like: if (customer.IsMatched) DisplayTextOnWeb(customer.SomeMatchedValue); My first thought for this was to add a couple interfaces on top of Customer that would only expose the properties and behaviors of the current state, and then only deal with those interfaces. The problem with this approach is that there seems to be no good way to move from an ICustomerWithNoMatchedValues to an ICustomerWithMatchedValues without doing direct casts, etc... (or at least I can't find one). I can't be the first to have come across this, how do you normally approach this? As a last caveat, I would like for this solution to play nice with FluentNHibernate :) Thanks in advance...

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  • JMS template credentials default value

    - by Gandalf StormCrow
    Hello everyone I'm trying to work with jboss messaging, does anyone knows the default value for these java.naming.security.principal and java.naming.security.credentials or how can I set them? <bean id="jndiTemplate" class="org.springframework.jndi.JndiTemplate"> <property name="environment"> <props> <prop key="java.naming.factory.initial">org.jnp.interfaces.NamingContextFactory</prop> <prop key="java.naming.provider.url">jnp://localhost:8080</prop> <prop key="java.naming.factory.url.pkgs">org.jboss.naming:org.jnp.interfaces</prop> <prop key="java.naming.security.principal">value</prop> <prop key="java.naming.security.credentials">value</prop> </props> </property> </bean> I'm trying to instansiate the <bean id="connectionFactory" class="org.springframework.jndi.JndiObjectFactoryBean"> I'm guessing that this is the cause why jboss timeouts when starts

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  • Object Oriented Programming in AS3

    - by Jordan
    I'm building a game in as3 that has balls moving and bouncing off the walls. When the user clicks an explosion appears and any ball that hits that explosion explodes too. Any ball that then hits that explosion explodes and so on. My question is what would be the best class structure for the balls. I have a level system to control levels and such and I've already come up with working ways to code the balls. Here's what I've done. My first attempt was to create a class for Movement, Bounce, Explosion and finally Orb. These all extended each other in the order I just named them. I got it working but having Bounce extend Movement and Explosion extend Bounce, it just doesn't seem very object oriented because what if I wanted to add a box class that didn't move, but did explode? I would need a separate class for that explosion. My second attempt was to create Movement, Bounce and Explosion without extending anything. Instead I passed in a reference to the Orb class to each. Then the class stores that reference and does what it needs to do based on events that are dispatched by the Orb such as update, which was broadcast from Orb every enter frame. This would drive the movement and bounce and also the explosion when the time came. This attempt worked as well but it just doesn't seem right. I've also thought about using Interfaces but because they are more of an outline for classes, I feel like code reuse goes out the window as each class would need its own code for a specific task even if that task is exactly the same. I feel as if I'm searching for some form of multiple inheritance for classes that as3 does not support. Can someone explain to me a better way of doing what I'm attempting to do? Am I being to "Object Oriented" by having classed for Movement, Bounce, Explosion and Orb? Are Interfaces the way to go? Any feedback is appreciated!

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  • How to name multiple versioned ServiceContracts in the same WCF service?

    - by Tor Hovland
    When you have to introduce a breaking change in a ServiceContract, a best practice is to keep the old one and create a new one, and use some version identifier in the namespace. If I understand this correctly, I should be able to do the following: [ServiceContract(Namespace = "http://foo.com/2010/01/14")] public interface IVersionedService { [OperationContract] string WriteGreeting(Person person); } [ServiceContract(Name = "IVersionedService", Namespace = "http://foo.com/2010/02/21")] public interface IVersionedService2 { [OperationContract(Name = "WriteGreeting")] Greeting WriteGreeting2(Person2 person); } With this I can create a service that supports both versions. This actually works, and it looks fine when testing from soapUI. However, when I create a client in Visual Studio using "Add Service Reference", VS disregards the namespaces and simply sees two interfaces with the same name. In order to differentiate them, VS adds "1" to the name of one of them. I end up with proxies called ServiceReference.VersionedServiceClient and ServiceReference.VersionedService1Client Now it's not easy for anybody to see which is the newer version. Should I give the interfaces different names? E.g IVersionedService1 IVersionedService2 or IVersionedService/2010/01/14 IVersionedService/2010/02/21 Doesn't this defeat the purpose of the namespace? Should I put them in different service classes and get a unique URL for each version?

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  • Bind WCF webservice to specific network interface / IP

    - by Markus
    On a machine with multiple network cards I need to bind a WCF webservice to a specific network interface. It seems that the default is to bind on all network interfaces. The machine has two network adapters with the IPs 192.168.0.10 and 192.168.0.11. I have an Apache running that binds on 192.168.0.10:80 and need to run the webservice on 192.168.0.11:80. (Due to external circumstances I cannot choose another port.) I tried the following: string endpoint = "http://192.168.0.11:80/SOAP"; ServiceHost = new ServiceHost(typeof(TService), new Uri(endpoint)); ServiceHost.AddServiceEndpoint(typeof(TContract), Binding, ""); // or: ServiceHost.AddServiceEndpoint(typeof(TContract), Binding, endpoint); But it doesn't work; netstat -ano -p tcp always shows the webservice listening on 0.0.0.0:80, which is all interfaces (if I got that correct). When I start Apache first, it correctly binds to the other interface, which in turn prevents the WCF service to bind to "all". Any ideas?

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  • Interface vs Abstract Class (general OO)

    - by Kave
    Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

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  • Extension methods for encapsulation and reusability

    - by tzaman
    In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself?

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  • C# Fun with Generics - Mutual Dependencies

    - by Kenneth Cochran
    As an experiment I'm trying to write a generic MVP framework. I started with: public interface IPresenter<TView> where TView: IView<IPresenter<... { TView View { get; set;} } public interface IView<TPresenter> where TPresenter:IPresenter<IView<... { TPresenter Presenter { get; set; } } Obviously this can't work because the types of TView and TPresenter can't be resolved. You'd be writing Type<Type<... forever. So my next attempt looked like this: public interface IView<T> where T:IPresenter { ... } public interface IView:IView<IPresenter> { } public interface IPresenter<TView> where TView: IView { ... } public interface IPresenter: IPresenter<IView> { ... } This actually compiles and you can even inherit from these interfaces like so: public class MyView : IView, IView<MyPresenter> { ... } public class MyPresenter : IPresenter, IPresenter<MyView> { ... } The problem is in the class definition you have to define any members declared in the generic type twice. Not ideal but it still compiles. The problem's start creeping up when you actually try to access the members of a Presenter from a View or vice versa. You get an Ambiguous reference when you try to compile. Is there any way to avoid this double implementation of a member when you inherit from both interfaces? Is it even possible to resolve two mutually dependent generic types at compile time?

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  • F# and statically checked union cases

    - by Johan Jonasson
    Soon me and my brother-in-arms Joel will release version 0.9 of Wing Beats. It's an internal DSL written in F#. With it you can generate XHTML. One of the sources of inspiration have been the XHTML.M module of the Ocsigen framework. I'm not used to the OCaml syntax, but I do understand XHTML.M somehow statically check if attributes and children of an element are of valid types. We have not been able to statically check the same thing in F#, and now I wonder if someone have any idea of how to do it? My first naive approach was to represent each element type in XHTML as a union case. But unfortunately you cannot statically restrict which cases are valid as parameter values, as in XHTML.M. Then I tried to use interfaces (each element type implements an interface for each valid parent) and type constraints, but I didn't manage to make it work without the use of explicit casting in a way that made the solution cumbersome to use. And it didn't feel like an elegant solution anyway. Today I've been looking at Code Contracts, but it seems to be incompatible with F# Interactive. When I hit alt + enter it freezes. Just to make my question clearer. Here is a super simple artificial example of the same problem: type Letter = | Vowel of string | Consonant of string let writeVowel = function | Vowel str -> sprintf "%s is a vowel" str I want writeVowel to only accept Vowels statically, and not as above, check it at runtime. How can we accomplish this? Does anyone have any idea? There must be a clever way of doing it. If not with union cases, maybe with interfaces? I've struggled with this, but am trapped in the box and can't think outside of it.

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  • Where is the Open Source alternative to WPF?

    - by Evan Plaice
    If we've learned anything from HTML/CSS it's that, declarative languages (like XML) work best to describe User Interfaces because: It's easy to build code preprocessors that can template the code effectively. The code is in a well defined well structured (ideally) format so it's easy to parse. The technology to effectively parse or crawl an XML based source file already exists. The UIs scripted code becomes much simpler and easier to understand. It simple enough that designers are able to design the interface themselves. Programmers suck at creating UIs so it should be made easy enough for designers. I recently took a look at the meat of a WPF application (ie. the XAML) and it looks surprisingly familiar to the declarative language style used in HTML. It's blindingly apparent to me that the current state of desktop UI development is largely fractionalized, otherwise there wouldn't be so much duplicated effort in the domain of user interfaces (IE. GTK, XUL, Qt, Winforms, WPF, etc). There are 45 GUI platforms for Python alone It's painfully obvious to me that there should be a general purpose, open source, standardized, platform independent, markup language for designing desktop GUIs. Much like what the W3C made HTML/CSS into. WPF, or more specifically XAML seems like a pretty likely step in the right direction. Why hasn't anyone in the Open Source community (AFAIK) even scratched the surface of this issue. Now that the 'browser wars' are over should we look forward to a future of 'desktop gui wars?' Note: This topic is relatively subjective in the attempt to be 'future-thinking.' I think that desktop GUI development in its current state sucks ((really)hard) and, even though WPF is still in it's infancy, it presents a likely solution to the problem. Has no one in the OS community looked into developing something similar because they don't see the value, or because it's not worth the effort?

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  • Visual Studio - Edit source code located in a database

    - by mfeingold
    I am building something similar to Server Explorer for Apache CouchDB. One of the things necessary is to be able to edit CouchDB view definitions which in CouchDB are JavaScript functions. How can I trick Visual Studio into using my object to retrieve and save the content of the JavaScript function but still use the rest of it - I am happy with editor itself and have no intention of writing my own Editor/Language Service, etc. The latter would be much bigger effort than what this project warrants Edit After more digging I am still stuck. Here is what I know: IVsUIShellOpenDocument interface provides a method OpenStandardEditor which can be used to open the standard Visual Studio editor. As one of the parameters this method takes a Pointer to the IUnknown interface of the document data object. This object is supposed to implement several interfaces described in many places all over the MSDN. Visual Studio SDK also provides a 'sample' implementation of the document data object VsTextBufferClass. I can create an instance of this class and when I pass the pointer to the instance to the OpenStandardEditor I can see my editor and it seems to work ok. When I try to implement my own class implementing the same interfaces (IVsTextBuffer, VsTextBuffer, IVsTextLines) OpenStandardEditor method returns success, but VS bombs out on call editor.Show() with an access violation. My suspicion is that VsTextBufferClass also implements some other interface(s) but not in C# way but rather in the good old COM way. I just do not know which one(s). Any thoughts?

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  • Is this WPF error handling a good idea ?

    - by Adiel
    I have a multi threaded wpf application with various HW interfaces. I want to react to several HW failures that can happen. For example : one of the interfaces is a temperature sensor and i want that from a certain temp. a meesage would appear and notify the user that it happened. i came up with the follwing design : /// <summary> /// This logic reacts to errors that occur during the system run. /// The reaction is set by the component that raised the error. /// </summary> public class ErrorHandlingLogic : Logic { } the above class would consume ErrorEventData that holds all the information about the error that occurred. public class ErrorEventData : IEventData { #region public enum public enum ErrorReaction { } #endregion public enum #region Private Data Memebers and props private ErrorReaction m_ErrorReaction; public ErrorReaction ErrorReactionValue { get { return m_ErrorReaction; } set { m_ErrorReaction = value; } } private string m_Msg; public string Msg { get { return m_Msg; } set { m_Msg = value; } } private string m_ComponentName; public string ComponentName { get { return m_ComponentName; } set { m_ComponentName = value; } } #endregion Private Data Memebers and props public ErrorEventData(ErrorReaction reaction, string msg, string componenetName) { m_ErrorReaction = reaction; m_Msg = msg; m_ComponentName = componenetName; } } the above ErrorHandlingLogic would decide what to do with the ErrorEventData sent to him from various components of the application. if needed it would be forwarded to the GUI to display a message to the user. so what do you think is it a good design ? thanks, Adiel.

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  • Fun with casting and inheritance

    - by Vaccano
    NOTE: This question is written in a C# like pseudo code, but I am really going to ask which languages have a solution. Please don't get hung up on syntax. Say I have two classes: class AngleLabel: CustomLabel { public bool Bold; // code to allow the label to be on an angle } class Label: CustomLabel { public bool Bold; // Code for a normal label // Maybe has code not in an AngleLabel (align for example). } They both decend from this class: class CustomLabel: Control { protected bool Bold; } The bold field is exposed as public in the descended classes. No interfaces are available on the classes. Now, I have a method that I want to beable to pass in a CustomLabel and set the Bold property. Can this be done without having to 1) find out what the real class of the object is and 2) cast to that object and then 3) make seperate code for each variable of each label type to set bold. Kind of like this: public void SetBold(customLabel: CustomLabel) { AngleLabel angleLabel; NormalLabel normalLabel; if (angleLabel is AngleLabel ) { angleLabel= customLabel as AngleLabel angleLabel.Bold = true; } if (label is Label) { normalLabel = customLabel as Label normalLabel .Bold = true; } } It would be nice to maybe make one cast and and then set bold on one variable. What I was musing about was to make a fourth class that just exposes the bold variable and cast my custom label to that class. Would that work? If so, which languages would it work for? (This example is drawn from an old version of Delphi (Delphi 5)). I don't know if it would work for that language, (I still need to try it out) but I am curious if it would work for C++, C# or Java. If not, any ideas on what would work? (Remember no interfaces are provided and I can not modify the classes.) Any one have a guess?

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  • Multiple exports with MEF does some really heinous stuff -- why, and why is it allowed?

    - by Dave
    I have an interesting situation where I need to do something like this: [Export[typeof(ICandy1)] [Export[typeof(ICandy2)] public class Candy : ICandy2 { ... } where public interface ICandy1 { ... } public interface ICandy2 : ICandy1 { ... } I couldn't find any posts anywhere regarding using multiple [Export] attributes, so I figured, what the hell, might as well try it. At first glance, it actually seemed to work. I have a couple of methods that call into both interfaces of a Candy instance, and it was fine. However, as I started to test the app, I saw that the behavior wasn't right, and when looking at the Output window, I saw that I was getting tons of COMExceptions. I couldn't track down where they were all coming from, but they always occurred when a worker thread was sleeping. I figured that it had to be from the main thread, then, but didn't know how to debug this at all. Nothing should have been going on in the GUI, and I disabled my DispatchTimers just in case -- same thing. Even more strange than the COMExceptions was the really, really erratic behavior when stepping through code. About 30% of the time, when I single stepped, it would pop out of the method, or it would single step over two lines of code! Totally weird stuff that I am not used to seeing. The only thing that changed between working and non-working code was the introduction of MEF through my plugin loading code. So as a test, I changed my plugin assembly to only export one interface, and I hardcoded everything in the app that relied on the other (now not-implemented) interface. And now the COMExceptions are gone, and the weird debugging behavior is gone. Is this something people here have seen before? If MEF is not expected to allow a class to Export multiple interfaces, then shouldn't a CompositionException get raised when composing the parts? Can anyone explain why MEF would cause these weird problems???

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  • How to Implement an Interface that Requires Duplicate Member Names?

    - by Will Marcouiller
    I often have to implement some interfaces such as IEnumerable<T> in my code. Each time, when implementing automatically, I encounter the following: public IEnumerator<T> GetEnumerator() { // Code here... } public IEnumerator GetEnumerator1() { // Code here... } Though I have to implement both GetEnumerator() methods, they impossibly can have the same name, even if we understand that they do the same, somehow. The compiler can't treat them as one being the overload of the other, because only the return type differs. When doing so, I manage to set the GetEnumerator1() accessor to private. This way, the compiler doesn't complaint about not implementing the interface member, and I simply throw a NotImplementedException within the method's body. However, I wonder whether it is a good practice, or if I shall proceed differently, as perhaps a method alias or something like so. What is the best approach while implementing an interface such as IEnumerable<T> that requires the implementation of two different methods with the same name? EDIT #1 Does VB.NET reacts differently from C# while implementing interfaces, since in VB.NET it is explicitly implemented, thus forcing the GetEnumerator1(). Here's the code: Public Function GetEnumerator() As System.Collections.Generic.IEnumerator(Of T) Implements System.Collections.Generic.IEnumerable(Of T).GetEnumerator // Code here... End Function Public Function GetEnumerator1() As System.Collections.Generic.IEnumerator Implements System.Collections.Generic.IEnumerable.GetEnumerator // Code here... End Function Both GetEnumerator() methods are explicitly implemented, and the compile will refuse them to have the same name. Why?

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  • Importing data from third party datasource (open architecture design )

    - by mare
    How would you design an application (classes, interfaces in class library) in .NET when we have a fixed database design on our side and we need to support imports of data from third party data sources, which will most likely be in XML? For instance, let us say we have a Products table in our DB which has columns Id Title Description TaxLevel Price and on the other side we have for instance Products: ProductId ProdTitle Text BasicPrice Quantity. Currently I do it like this: Have the third party XML convert to classes and XSD's and then deserialize its contents into strong typed objects (what we get as a result of this process is classes like ThirdPartyProduct, ThirdPartyClassification, etc.). Then I have methods like this: InsertProduct(ThirdPartyProduct newproduct) I do not use interfaces at the moment but I would like them to. What I would like is implement something like public class Contoso_ProductSynchronization : ProductSynchronization InsertProduct(ContosoProduct p) where ProductSynchronization will be an interface or abstract class. There will most likely be many implementations of ProductSynchronization. I cannot hardcode the types - classes like ContosoProduct, NorthwindProduct might be created from the third party XML's (so preferably I would continue to use deserialization). Hopefully someone will understand what I'm trying to explain here. Just imagine you are the seller and you have numerous providers and each one uses their own proprietary XML format. I don't mind the development, which will of course be needed everytime new format appears, because it will only require 10-20 methods to be implemented, I just want the architecture to be open and support that.

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