Create generic delegate using reflection

Question

I have the following code:

class Program
{
    static void Main(string[] args)
    {
        new Program().Run();
    }

    public void Run()
    {
        // works
        Func<IEnumerable<int>> static_delegate = new Func<IEnumerable<int>>(SomeMethod<String>);

        MethodInfo mi = this.GetType().GetMethod("SomeMethod").MakeGenericMethod(new Type[] { typeof(String) });
        // throws ArgumentException: Error binding to target method
        Func<IEnumerable<int>> reflection_delgate = (Func<IEnumerable<int>>)Delegate.CreateDelegate(typeof(Func<IEnumerable<int>>), mi);

    }

    public IEnumerable<int> SomeMethod<T>()
    {
        return new int[0];
    }
}

Why can't I create a delegate to my generic method? I know I could just use mi.Invoke(this, null), but since I'm going to want to execute SomeMethod potentially several million times, I'd like to be able to create a delegate and cache it as a small optimization.

Reed Copsey · Accepted Answer · 2010-03-10 19:10:21Z

9

You method isn't a static method, so you need to use:

Func<IEnumerable<int>> reflection_delgate = (Func<IEnumerable<int>>)Delegate.CreateDelegate(typeof(Func<IEnumerable<int>>), this, mi);

Passing "this" to the second argument will allow the method to be bound to the instance method on the current object...

answered Mar 10, 2010 at 19:10

Reed Copsey

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1 Comment

Dathan Over a year ago

Doh! Thanks a bunch - don't know how I missed that.

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