如何通过扩展重载泛型方法的反映获得方法？

Question

public static M MustNotEqual<M, T, R>(this IMustPassRule<M, T, R> mpr, R value)
{
    return mpr.MustPassRule(new NotEqualRule<R>(value));
}

public static M MustNotEqual<M, T, R>(this IMustPassRule<M, T, R> mpr, R value, IEqualityComparer<R> comparer)
{
    return mpr.MustPassRule(new NotEqualRule<R>(value, comparer));
}

How to get through reflection first method for example?

Answer 1

If the parameter wouldn't be generic type you could use this overload of GetMethod and pass a type array to match parameter types.In this case I would do it using linq:

yourType.GetMethods(BindingFlags.Static | BindingFlags.Public)
        .FirstOrDefault(m => m.Name == "MustNotEqual" &&
                             m.GetParameters().Length == 2);

Ofcourse you can improve this to match the parameter types, this is just an example.To see why GetMethod is not an option you can have a look at this question .

Answer 2

Finding the extension methods that apply to a class is quite tricky. When you call an extension method the compiler will look at all the types in scope which have methods with an ExtensionAttribute on them. This extension is automatically added by the compiler when it compiles an extension method.

Trying to resolve them at runtime is difficult as there is no concept of what namespaces are in scope when your code executes - all you've got is your class and it isn't necessarily tied to the extension method. If you want to search a particular class for an extension method then that's easy, you just use GetMethod with the appropriate BindingFlags and check the Extension attribute if you want to be really thorough. However, if this isn't the case then you'll need to enumerate all the assemblies currently loaded searching for public classes that have a static method with the Extension attribute that matches your parameter criteria.