Question

I’m generating new type at runtime,
After I’ve generated default constructor I want to generate another one, with parameters.I’m doing it this way :

cb = tb.DefineConstructor(MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
                    CallingConventions.Standard, new Type[] { typeof(bool) });
GenConstructorWithParameters(cb, fields, genFields);

The problem is, that I am unable to call default constructor from method GenConstructorWithParameters, because CLR does not allow me to write something like this :

gen.Emit(OpCodes.Ldarg_0);        
gen.Emit(OpCodes.Call, cb.DeclaringType.GetConstructor(Type.EmptyTypes));//Not allowed to call .GetConstructor() on not created type!

How do I emit call to default constructor? Is it possible at all?

tb – instance of TypeBuilder, cb – ConstructorBuilder

Answer 1

Rather than using DeclaringType.GetConstructor, you should pass your current ConstructorBuilder for the default constructor.

Basically, whilst building up a type, in places where you might use reflection based methods on existing types, you should instead pass in the builders that you’re already working with.

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So it would be:

gen.Emit(OpCodes.Call, defaultCB);

where defaultCB was the ConstructorBuilder you declared when defining the default constructor.