dynamic delegate to pass a method as parameter in C#

Question

Is there any way to use DLR to reference a method in C#?

In dynamic languages like JavaScript or Python I could easily pass a method as an argument to another method. In C# being statically typed language, I either use Delegate type which needs lots of casting:

public static void AddMethod(Delegate del)
{
    // implementation
}

and then use casting whenever I call this method

static void Main(string[] args)
{
    AddMethod(new Func<object, bool>(Test));
}

public static bool Test(object obj)
{
    return true;
}

Or, I need to define dozens of overloads to satisfy any method calls:

public static void AddMethod<TResult>(Func<TResult> method)
{
}

public static void AddMethod<T, TResult>(Func<T, TResult> method)
{
}

public static void AddMethod<T1, T2, TResult>(Func<T1, T2, TResult> method)
{
}

public static void AddMethod<T1, T2, T3, TResult>(Func<T1, T2, T3, TResult> method)
{
}

Is there any cleaner way to define an argument as a placeholder for all other methods? (I'm trying to avoid MethodInfo or other Reflection stuff here)

I was trying something like this:

public delegate dynamic DynamicDelegate(params dynamic[] args);

public static void AddMethod(DynamicDelegate method)
{
}

But the compiler doesn't seem to accept a statically typed method for a dynamically declared delegates!

Any other thoughts?

Answer 1

You can use a simple Action

void AddMethod(Action action) //or void AddMethod(Func<TResult> fxn)
{
}

and call as

AddMethod(()=>Test(obj));   

or

AddMethod(()=>Test(obj1,obj2));   

--EDIT--

AddMethod(() => Math.Max(1,3));  
AddMethod(() => (int)Math.Sqrt(4));
AddMethod(() => new int[]{8,5,6}.Min())

void AddMethod(Func<int> fxn)
{
     int i = fxn() * fxn();  // <---
}

Answer 2

Since .NET doesn't allow delegates with an unknown parameter syntax (this would approximate C void pointers, which is not something you want in a type-safe language), the closest thing that allows a variable argument list would be to pass an array of object arguments (i.e. object MyMethod(params object[] args)).
However, since this array is also an object reference, you can suffice with a single object reference:

object MyMethod(object arg))

The .NET framework also does this, see e.g. the ParameterizedThreadStart delegate)

So the basic idea is that you require that the user writes his code as a method that matches the above signature, and in turn it can receive any variable list of arguments of any type or size.