订阅作为方法参数传递的委托

Question

I'm attempting to build a recurring programming pattern into a generic class for code re-use. Part of this pattern thread-safely subscribes/unsubscribes to a delegate as needed during asynchronous operations (multicast delegate used as event).

The following code does not compile. The problem I'm facing is that C# allows me to pass a delegate as method argument, but anywhere inside MyWorker class the subscribe +=,-= operations cause errors. (Works fine on the same delegate from outside).

[Operator '+=' cannot be applied to operands of type 'delegateT' and 'method group']

Syntactical errors? delegate scope limitation? is this disallowed by the language?

public class MyWorker<delegateT,argT>
{
    private delegateT mDelegate;

    public MyWorker(delegateT d)
    {
        mDelegate = d; //save delegate (reference?) for use later
    }

    public void DoWorkAsync()
    {
        mDelegate += m_subscriber; //ERROR: Operator '+=' cannot be applied to operands of type 'delegateT'...

        //...Do some work that causes delegate to fire...

        mDelegate -= m_subscriber; //ERROR: Operator '-=' cannot be applied to operands of type 'delegateT'...
    }

    private void m_subscriber(argT arg)
    {
        Console.WriteLine("Received: " + arg.ToString());
    }
}

Note that generics do not seem to be the cause; I've tried using static types instead with the same result. I've also tried passing delegate with the 'ref' keyword to make sure i'm storing and referencing the original object rather than a local copy...maybe a secondary issue, but one step at a time.

[UPDATE]

OIC, inability to constrain Delegate type seems to be a major issue here, and prevents generic usage the way I'm doing it. Thanks for pointing that out Ron.

To clarify the original intent:
I use delegates for internal events; more flexibility than strict 'event' type. I'm searching for some way to pass a delegate (ref?) to MyWorker class at runtime. Then MyWorker performs some background tasks which subscribe and unsubscribe as necessary to receive events during operation, before finally exiting for garbage collection. I do this for 30+ nearly identical tasks/events, which is why creating a reusable (generic?) class is highly desirable.

Delegates in my system have a strict form such as:

delegate void delegateEvent1(Class1 arg);
delegate void delegateEvent2(Class2 arg);
...
delegate void delegateEventN(ClassN arg);

Plan B is to pass Action delegates to subscribe and unsubscribe from within MyWorker. This is quite a bit messier as it requires 2 Actions<> to be created for each invocation rather than just cleanly passing the desired delegate.

Open to any suggestions...

Answer 1

It's not because you named your generic parameter delegateT compiler knows it's some delegate type and so it can't know that some += operator exists on that type. It would need some generic constraint to enforce this ; but AFAIK that's not possible in C#

As KiwiPiet pointed in comment you can maybe try to add a constraint for some delegate type though
As pointed by Ron Beyer in comment it's also not possible to constraint to some delegate type too