How to call a method overload based on closed generic type?

Question

Suppose I have three methods:

void Foo(MemoryStream v) {Console.WriteLine (\"MemoryStream\");}
void Foo(Stream v)       {Console.WriteLine (\"Stream\");}
void Fo         


        

Answer 1

I had the same issue, and the unique solution I knew was try-casting it until I got something other than null. Then, I would have the correct type at compile time and the compiler would know the right overload to call. I could not find another way to achieve this 'run-time polymorphism'.

To avoid using a dictionary or a switch-like solution (poor maintainability,as pointded out by Marc), just call Method((dynamic) o) and DLR will call the correct overload method according to the run-time type.

Just remember to:

1) Provide a default overload with the most top type possible;

2) Watch out for any ambiguity during resolution of type at run-time (i.e. two indepenent interfaces and one implementation that uses both);

3) Handle null case.

You can read more about it here.

Hope I've helped.