Delegates x++ interop .NET

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Posted on by Community Member

Hi all,

I'd like to know if there is an easy way to map .NET delegates on X++. I know that X++ delegates don't return a value so this is not a viable use, but since they can be (and are) marshaled on .NET classes and used on X++ (though IL code) I'd like to know if somebody could show me an example.

More specifically I am trying to use tasks like the example below...

Task<int> task1 = new Task<int>(() =>

{

int result = 1;

for (int i = 1; i < 10; i++)

result *= i;

return result;

});

Anyway think this last code would be encapsulated on .NET code and what I must pass to .NET would be the X++ code.So that would be something like:

MyClassOnDotNetInteroped.PassADelegateFromXPlusPlus(MyDelegateOrHandlerOnXPlusPlus);

private int MyDelegateOrHandlerOnXPlusPlus()

{

}

How this could be achieved through X++?

Thanks and hope I explained properly my problem.

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Martin Dráb 237,985 Most Valuable Professional on at

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AX 7 supports working with tasks, but there still no support for delegates (in usual sense) in X++ (not mentioning lambda functions), therefore you have to pass name of a static method (and its class) to be called. You could do something similar in AX 2012.

Nevertheless if you can, move your code creating the task to a Visual Studio project. There you can use use proper .NET delegates and if you need something from AX, just use AX proxy classes.

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Thanks so much! Indeed I managed to work.

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Community Member on at

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BTW,

Is there also a way to deal with generics on function calls? So for example how this function could be translated to X++? (where TMessage is the generic type)

Handle<TMessage>(Func<TMessage, Task> handlerFunction)

Thanks

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Martin Dráb 237,985 Most Valuable Professional on at

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If my reply answered your question, please mark it as the verified answer. Otherwise please share your solution with us and mark that as the answer.

Generics isn't supported by X++ either. You surely can assign a generic type to a variable of a compatible type, and you can even create instance of generic types via System.Activator (which is undeniably ugly). Again, my recommendation is wrapping these things in a .NET library and using C#, which does support generics. It's really easy thanks to VS projects in AOT.

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Hi,

I tried the code on X++ and seems to not work...Am In missing something, or actually you really cannot work with simple delegates? This is the example:

public class A

{

System.Threading.Tasks.Task taskResult;

public static void DoNothing()

{

}

public System.Threading.Tasks.Task Handle()

{

taskResult = new System.Threading.Tasks.Task(DoNothing);

return taskResult;

}

}

Trying to pass the DoNothing function does not work (it does on C#), and no way with Static references on the function definition, class...

Thanks so much....

P.S.: I am a .NET developer and I am making a library to be consumed from X++, so X++ programmers can work with that, so moving code to X++ (for the X++ programmers is not an option...They are working with Dynamics 2012 R3).

So if X++ interop is so limited on .NET I'd go on another way...

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Martin Dráb 237,985 Most Valuable Professional on at

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As I said, there is no support for delegates (in CLR sense) in X++, therefore your code can't ever work. It depends on delegates and also on C# syntax for converting method groups to delegates. There is nothing like that in X++.

Sorry, I should have explained the solution in better detail. If you get a class name and a method name, you can call the method via reflection. Then you could create .NET method doing this call and pass it to a task in C# code. If you want a generic solution, you may have a method that accepts a class/method to call (and possibly a callback class/method) and returns a task. That's exactly how runAsync() in AX7 works.

I also suggested that you avoided that; you might be able to move the whole logic to your C# class library (avoiding calls from .NET to AX completely), or write a method that calls appropriate X++ objects through proxy classes, instead of building something generic with reflection.

I didn't suggest to move your code to X++. I suggested exactly the opposite - stop trying to play with delegates and generics in X++ and do it in C#. You're writing a library to be used from X++, therefore you don't want to expose anything that can't be consumed there, therefore keep all such concepts hidden in your library and expose a simplified public interface. I use this approach myself.

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epihodi 31 on at

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Hello everyone.

Maybe someone know some .Net library to call it from Ax and use HttpClient?

Or each developer write it for himself?

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Martin Dráb 237,985 Most Valuable Professional on at

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Hi Anton, your question doesn't seem to be about delegates, therefore please create a new thread (with an appropriate title and tags) and we can discuss your problem there.

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