Can I change a function/method definition in C#? (redefine, not override)

Question

Is there a way to redefine a function definition/method in C#?

Situation:

Modding someone else's code, and they have:

namespace TheirCode 
{
  public static class SomeUtility
  {
    public static void A(this Thing thing) 
    {
      //do something I want to change
    }
  }
}

I can load another dll that will allow me to insert my own code...but I want to change the behavior of a_thing.A(); I need the changes to affect all Things, not just any derived NewThings I might create.

Can I rewrite the method definition somehow? Can I change the behavior another way?

Thanks

You're not clear about whether `A()` is static or not. It matters a little. And is their assembly signed? Open source? — Henk Holterman, Jul 29 '18 at 19:27
Here recompiling would involve replacing the author's .dll with my own .dll, instead of just creating my own additional .dll to be loaded? — Peter Kay, Jul 29 '18 at 19:32
Yes. And when it's signed you better have control over all dependent pieces. — Henk Holterman, Jul 29 '18 at 19:34
Loks to be possible, but looks noz to be simple at all: https://www.codeproject.com/Articles/37549/CLR-Injection-Runtime-Method-Replacer — ZorgoZ, Jul 29 '18 at 20:27
Look in to the terminology "code weaving" and the library `Mono.Cecil`, that may help you get started. — Scott Chamberlain, Jul 29 '18 at 20:46

score 0 · Answer 1 · answered Jul 30 '18 at 16:02

Oh wow, there's a whole series of answers in this other question:

Dynamically replace the contents of a C# method?

The Harmony answer looks great!

I don't know why I couldn't find it earlier when I was searching; maybe this question's search terms will help someone else.

Can I change a function/method definition in C#? (redefine, not override)

1 Answers1