CODEWITHSUNDEEP
c#ambiguous
Simon
Simon

Reputation: 8357

How can I make a MethodCallExpression for a method?

If I have a method name, and the parameters for the method, how can I create a MethodCallExpression for the method?

Here is an example method:

public void HandleEventWithArg(int arg) 
{ 

}

Here is the code that I have:

var methodInfo = obj.GetType().GetMethod("HandleEventWithArg");
var body = Expression.Call(Expression.Constant(methodInfo), methodInfo.GetType().GetMethod("Invoke"), argExpression);

Here is the exception:

An unhandled exception of type 'System.Reflection.AmbiguousMatchException' occurred in mscorlib.dll

Additional information: Ambiguous match found.

Upvotes: 3

Views: 2797

Answers (1)

Jcl
Jcl

Reputation: 28272

I'm not sure if this is ok with you, but your construction of the call expression looks wrong to me (you are trying to create a expression that calls your method info's Invoke method, instead of the actual method on your type.

To create a expression that calls your method on your instance, do this:

var methodInfo = obj.GetType().GetMethod("HandleEventWithArg");

// Pass the instance of the object you want to call the method
// on as the first argument (as an expression).
// Then the methodinfo of the method you want to call.
// And then the arguments.
var body = Expression.Call(Expression.Constant(obj), methodInfo, argExpression);

I've made a fiddle

PS: I'm guessing argExpression is an expression with the int that your method expects

Upvotes: 2

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