Question

Assume I have a class like so:

public class MyClass<T>
{
    public void Foo(T t)
    {
    }
}

Now, assume, I have an instance of MyClass<int> and a MethodInfo of its Foo method.
Calling methodInfo.GetParameters() will return a ParameterInfo array with one entry, referring to type int. My problem is, that I can’t seem to find out, if that parameter was declared as int in the class or as T.

What am I trying to achieve?
At runtime, I want to read the documentation of the method specified by MethodInfo from the XML Doc file generated by Visual Studio.
For the above defined method, the key looks like this:

<namespace>.MyClass`1.Foo(`0)

The `0 refers to the first generic type parameter of the declaring class. To be able to construct this string, I need to somehow get this information.
But how? MethodInfo doesn’t seem to contain that info…

Answer 1

The key seems to be Type.ContainsGenericParameters on the parameter type:

Given

public class MyClass<T>
{
    public void Foo(T t)
    {
    }

    public void Bar(int i)
    {

    }
}

Then

class Program
{
    static void Main(string[] args)
    {
        var obj = new MyClass<int>();

        // Closed type
        var closedType = obj.GetType();

        // Open generic (typeof(MyClass<>))
        var openType = closedType.GetGenericTypeDefinition();

        // Methods on open type
        var fooT = openType.GetMethod("Foo");
        var barint = openType.GetMethod("Bar");

        // Parameter types
        var tInFoo = fooT.GetParameters()[0].ParameterType;
        var iInBar = barint.GetParameters()[0].ParameterType;

        // Are they generic?
        var tInFooIsGeneric = tInFoo.ContainsGenericParameters;
        var iInBarIsGeneric = iInBar.ContainsGenericParameters;

        Console.WriteLine(tInFooIsGeneric);
        Console.WriteLine(iInBarIsGeneric);

        Console.ReadKey();
    }
}

outputs

True
False

This will obviously need more work for overloads and so on.