Get all Methods with a given return type

Question

Is this code wrong? It's just not returning anything:

public IEnumerable<string> GetMethodsOfReturnType(Type cls, Type ret)
{
   var methods = cls.GetMethods(BindingFlags.NonPublic);
   var retMethods = methods.Where(m => m.ReturnType.IsSubclassOf(ret))
                           .Select(m => m.Name);
   return retMethods;
}

It's returning an empty enumerator.

Note: I'm calling it on a ASP.NET MVC Controller looking for ActionResults

GetMethodsOfReturnType(typeof(ProductsController), typeof(ActionResult));

Answer 1

BindingFlags.NonPublic | BindingFlags.Instance

Where(m => ret == m.ReturnType || m.ReturnType.IsSubclassOf(ret))

Answer 2

Two changes that could possibly make this work:

public IEnumerable<string> GetMethodsOfReturnType(Type cls, Type ret)
{
   var methods = cls.GetMethods(BindingFlags.NonPublic | BindingFlags.Instance);
   var retMethods = methods.Where(m => m.ReturnType.IsSubclassOf(ret) || m.ReturnType == ret)
                           .Select(m => m.Name);
   return retMethods;
}

Answer 3

Others have pointed out fixes, but I'd like to suggest an alternative to IsSubclassOf as well as including public methods:

public IEnumerable<string> GetMethodsOfReturnType(Type cls, Type ret)
{
   // Did you really mean to prohibit public methods? I assume not
   var methods = cls.GetMethods(BindingFlags.NonPublic | 
                                BindingFlags.Public |
                                BindingFlags.Instance);
   var retMethods = methods.Where(m => m.ReturnType.IsAssignableFrom(ret))
                           .Select(m => m.Name);
   return retMethods;
}

With IsAssignableFrom, you don't need to have the extra "is the return type exactly the same as the desired type" test, and also it will work with interfaces.