Does C# support a __call__ method?

Question

Python has this magic __call__ method that gets called when the object is called like a function. Does C# support something similar?

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Specifically, I was hoping for a way to use delegates and objects interchangeably. Trying to design an API where a user can pass in a list of functions, but sometimes those functions need some initial params, in which case they'd use one of those callable objects instead.

Answer 1

Sure, if you inherit from DynamicObject. I think you're after TryInvoke which executes on obj(...), but there are several other method you can override to handle casting, index access (obj[idx]), method invocations, property invocations, etc.

using System;
using System.Diagnostics;
using System.Dynamic;
using System.Linq;
using System.Text;

namespace ConsoleApplication {
    public static class ConsoleApp {
        public static void Main() {
            dynamic x = new MyDynamicObject();
            var result = x("awe", "some");

            Debug.Assert(result == "awesome");
        }
    }

    public class MyDynamicObject : DynamicObject {
        public override Boolean TryInvoke(InvokeBinder binder, Object[] args, out Object result) {
            result = args.Aggregate(new StringBuilder(), (builder, item) => builder.Append(item), builder => builder.ToString());
            return true;
        }
    }
}