Generic collections type test

Question

I'd like to make some operations according to a given collection type (using reflexion), regardless of the generic type.

Here is my code:

    void MyFct(Type a_type)
    {
        // Check if it's type of List<>
        if (a_type.Name == "List`1")
        {
            // Do stuff
        }
        // Check if it's type of Dictionary<,>
        else if (a_type.Name == "Dictionary`2")
        {
            // Do stuff
        }
    }

It works for now, but it gets obvious to me that it's not the most safe solution.

    void MyFct(Type a_type)
    {
        // Check if it's type of List<>
        if (a_type == typeof(List<>))
        {
            // Do stuff
        }
        // Check if it's type of Dictionary<,>
        else if (a_type == typeof(Dictionary<,>))
        {
            // Do stuff
        }
    }

I tried that too, it actualy compiles but doesn't work... I also tried to test all interfaces of the given collection type, but it implies an exclusivity for interfaces in collections...

I hope I made myself clear, my english lack of training :)

I suspect you're trying to solve the wrong problem. Adding type-specific checks to generic code is smelly. — n8wrl, Apr 27 '12 at 18:04
* a_type.ToString() => System.Collections.Generic.List`1[MyClass] — s0ubap, Apr 27 '12 at 18:08
@s0ubap: That certainly explains why the test against "List`1" failed — n8wrl, Apr 27 '12 at 18:09
hum.. It actually works; a_type.Name is actually "List`1". I'm just wondering if it's the only solution, which seems "smelly" to me. — s0ubap, Apr 27 '12 at 18:14

score 9 · Accepted Answer · answered Apr 27 '12 at 18:06

If you want to see if something implements a specific generic type, then you would need to do this:

if(a_type.IsGenericType && a_type.GetGenericTypeDefinition() == typeof(List<>))

The GetGenericTypeDefinition() method will return the unbounded generic type for you test against.

Generic collections type test

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