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.NET Forum / .NET Framework / New Users / February 2008delegate in interfaces vb.net vs c#
Hi, I could define delegates in VB.NET code Public Interface Interface1 Delegate Function Abc() End Interface wherer as the following was not allowed in C# interface Interface1 { delegate void Abc(); } what could be reasons behing this being allowed in VB.NET and not in C#? I mean the question is from interface perspective... i could define delegate in vb.net interface but not in C#... Hi, I could define delegates in VB.NET code Public Interface Interface1 Delegate Function Abc() End Interface wherer as the following was not allowed in C# interface Interface1 { delegate void Abc(); } what could be reasons behing this being allowed in VB.NET and not in C#? > I could define delegates in VB.NET code > > Public Interface Interface1 > Delegate Function Abc() > End Interface Hmm, interesting. > wherer as the following was not allowed in C# > [quoted text clipped - 4 lines] > > what could be reasons behing this being allowed in VB.NET and not in C#? Interfaces don't allow nested types at all in C#, whether delegates or not. I'm not sure I've ever desired them, to be honest. I'm not sure it makes much sense. I'm quite surprised they're allowed in VB (and indeed in IL). I wonder if you can *use* a nested type defined like this from C#. Will try it another time...  SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk Thanks Jon. Though i am new here, I have seen many many many posts of yor over here ... thanks for your efforts for the community... Yes i could implement this vb interface in C# class, bind an event to this delegate 'handler' and execute this event... >> I could define delegates in VB.NET code >> [quoted text clipped - 20 lines] > if you can *use* a nested type defined like this from C#. Will try it > another time... > Thanks Jon. Though i am new here, I have seen many many many posts of yor > over here ... thanks for your efforts for the community... My pleasure - very literally. I wouldn't post if I didn't enjoy it :) > Yes i could implement this vb interface in C# class, bind an event to this > delegate 'handler' and execute this event... This is why it doesn't make much sense to me to have the delegate type in an interface - it's something that you wouldn't need to implement, because it's just a type declaration. If you want the interface to specify a member to be implemented (such as a property or event) which is *of* a particular type, that's a different matter. It's worth being clear about the difference between declaring a new delegate type, and declaring a variable/property/event of that type. Hopefully http://pobox.com/~skeet/csharp/events.html will help even though it's in C#. I'm sure the same things apply to VB. Just to clarify - do you have a VB interface which you need to implement in C#, or a slightly different situation? SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk No its exactly the same situation. One of our other team were having these VB.NET interfaces having these delegates in them. They wanted to implement these on C# interfaces and were fumbling with not being able to create these for C# (from rather wondring perspective to 'implement' those delegates). It came down to C# can not allow this being done and hence the query. :) >> Thanks Jon. Though i am new here, I have seen many many many posts of yor >> over here ... thanks for your efforts for the community... [quoted text clipped - 19 lines] > Just to clarify - do you have a VB interface which you need to > implement in C#, or a slightly different situation? > No its exactly the same situation. One of our other team were having these > VB.NET interfaces having these delegates in them. They wanted to implement > these on C# interfaces and were fumbling with not being able to create these > for C# (from rather wondring perspective to 'implement' those delegates). It > came down to C# can not allow this being done and hence the query. Just tried it, and basically you don't need to do anything with the delegate types. They're just extra types which are available. Here's an example: IFoo.vb: Public Interface IFoo Function GimmeString() As String Delegate Function Abc() As Object End Interface Foo.cs: class Foo : IFoo { public string GimmeString() { return "Yes"; } } Note that you don't need to "implement" IFoo.Abc. SignatureJon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet World class .NET training in the UK: http://iterativetraining.co.uk thanks :) >> No its exactly the same situation. One of our other team were having >> these [quoted text clipped - 28 lines] > > Note that you don't need to "implement" IFoo.Abc. thanks :) >> No its exactly the same situation. One of our other team were having >> these [quoted text clipped - 28 lines] > > Note that you don't need to "implement" IFoo.Abc. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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