Re: UDA question

[Dicebot]

On Tuesday, 16 April 2013 at 06:29:22 UTC, Ulf Johansson wrote:

I have a question regarding using a struct value as user-defined attribute. The use-case I am trying to get working is as follows:

struct message {
    int atom;
}

...

class AnActor : ... {
    @message(id) void myHandler(string arg1, real arg2) {
    }

    mixin ... // a mixin that builds message dispatch
}

The 'message' attribute defines methods of the class that will participate in message dispatch argument matching. This works fine but I want to take this one step further. I want to be able to give a message and a handler an ID that more strictly directs a message (and gives an error if arguments does not match).

The problem I have is quite simple - getting the value of 'atom' out of the message attribute. How can I do this? I did not post any of my actual code, I hope the above example describes the problem.

Regards,
Ulf

foreach(attribute, __traits(getAttributes, AnActor))
{
    static if (is(typeof(attribute) == message))
        pragma(msg, attribute.atom);
}