Dynamically create type and call constructor of base-class

Question

I need to create a class dynamically. Most things work fine but i\'m stuck in generating the constructor.

AssemblyBuilder _assemblyBuilder =
        AppDomai         


        

Answer 1

I think the problem is that you're trying to call the constructor of the open generic type GenericType<GT, TEventSource, TEventArgs>, but you need to call the constructor of the closed type BaseClass<MyType, ConcreteSourceType, ConcreteEventArgsType>. The solution to the seems simple:

var baseCtor = baseType.GetConstructor(
    BindingFlags.NonPublic | BindingFlags.Instance, null,
    new[] { typeof(string) }, null);

The problem is that this doesn't work and throws NotSupportedException. So, it seems getting the constructor of a generic type, where one of the parameters is a TypeBuilder is nut supported.

Because of that, I think what you want is not possible using Reflection.Emit, unless there is some hack to work around this.

EDIT: A-HA! I had to dive deep into Reflection.Emit in Reflector _{^{(although looking at the right place in the documentation would have worked too)}}, but I found it: there is a special method exactly for this: the static TypeBuilder.GetConstructor(). So this should work:

var baseNonGenericCtor = baseNotGenericType.GetConstructor(
    BindingFlags.NonPublic | BindingFlags.Instance, null,
    new[] { typeof(string) }, null);
var baseCtor = TypeBuilder.GetConstructor(baseType, baseNonGenericCtor);

Answer 2

The easiest way to do this would be to compile up your abstract and derived classes into a simple assembly, then open them in Reflector using the "Reflection.Emit" language available as a addin from:

http://reflectoraddins.codeplex.com/

Yes, that's as cool as it sounds :)