Comments on: Polymorphism in Expression trees

By: Jaime

Jaime — Thu, 26 Feb 2009 16:16:28 +0000

Would this do the trick?
body.Expression.Type == typeof(Child)

By: bogardj

bogardj — Wed, 25 Feb 2009 16:36:08 +0000

@Chad

Yeah, going off of typeof(Child) would work. Nate Kohari made my test pass:

http://pastie.org/399708

I see this as a crazy hack, and means I can’t trust any MemberInfo directly in an expression tree.

It’s also borked for MethodCallExpression as well.

By: chadmyers

chadmyers — Wed, 25 Feb 2009 15:32:01 +0000

Does the test work if you use string-based reflection? I’m probably wrong, but your assertion seems incorrect.

By: bogardj

bogardj — Wed, 25 Feb 2009 13:24:51 +0000

@Scott

That does let me get to the correct type of the parameter, but I’ll have to re-interrogate that type to get the correct MemberInfo. I ran into this trying to get attributes from a Property, and found it didn’t have the derived type’s MemberInfo.

By: Scott Allen

Scott Allen — Wed, 25 Feb 2009 01:57:55 +0000

Perhaps you should be looking at the parameter type for the expression instead of the declaring type of the property?

i.e.

((MemberExpression)func.Body).Expression.Type