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c#reflection.emitfastmember

Use emit to return null

I've been using the FastMember project. It contains this code:

il.Emit(OpCodes.Ldarg, 2); 
il.Emit(OpCodes.Newobj, typeof(ArgumentOutOfRangeException).GetConstructor(new[] { typeof(string) }));
il.Emit(OpCodes.Throw);

I would like to change that to just return null instead. I tried replacing it with a single line il.Emit(OpCodes.Ret);. However, I get invalid program errors using that. How do I set the return value to null using emitted code?

Solution

  • If you just emit ret, that's like return; in C#. But you need return null;

    You should use

    il.Emit(OpCodes.Ldnull);
il.Emit(OpCodes.Ret);