CODEWITHSUNDEEP
c#delegatesexpression-treeslinq-expressions
justin.m.chase
justin.m.chase

Reputation: 13665

Using linq expressions how can I create and return a delegate?

In C# I am attempting to use linq expressions to generate calls to certain methods. One of the parameters to the method is a delegate. I have the MethodInfo for the method I want to pass as a delegate I just am not sure of the linq syntax for creating delegates.

This is a bit contrived but I hope this shows what I'm trying to do:

[C#]
delegate void Example();

object instance = ...;
MethodInfo methodToCall = ...;
MethodInfo methodToReference = instance.GetType().GetMethod("Foo");
var lambda = Expression.Call(
    methodToCall,
    Expression.New(
      typeof(Example).GetConstructor(new [] { typeof(object), IntPtr }),
      Expression.Constant(instance),
      Expression.Constant(/* IntPtr from MethodInfo?? */)));

lambda.Compile()();

The problem is that the constructor for a delegate is asking for an IntPtr, I am not sure how to get that! Is there a more direct way to create a delegate object than trying to use the New() expression method?

Upvotes: 1

Views: 1816

Answers (1)

Lee
Lee

Reputation: 144136

Example e = (Example)Delegate.CreateDelegate(typeof(Example), instance, methodToReference);

Upvotes: 1

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