Question

If I have a method signature like this;

public void Execute(Action<T> action) {
    ...
}

but I want to constrain it so that the supplied ‘action’ only comes from the class ‘MyActions’, how can this be achieved in c#?

---

In order to try and make it clearer;

For example I have a class called MyActions;

public class MyActions {
    public void FirstAction<T>(T item) {
        ...
    }

    public void SecondAction<T>(T item) {
        ...
    }
}

I have the above method and I want it so that the only actions that the method will accept are those from this class.

I do not want it to be possible for anyone to supply an arbitrary action, they must come from the class ‘MyActions’.

Can it be done?

Regards,

Ryan.

Answer 1

One way to make clear your intent that you want to accept only members of MyActions would be something like:

public void Execute(Func<MyActions, Action<T>> actionSelector)

You could then call it like

Execute(actions => actions.SomeAction);

Of course, this works only if the methods (or delegate properties) of MyActions are not static.

And like I said, this makes your intent clear, but doesn’t actually constraint the methods, someone could still call your method like:

Execute(ignored => otherAction);

In general this seems to me like a weird thing to want.