[dmd-concurrency] Pattern matching on message receives, error handling

[Andrei Alexandrescu]

Sean Kelly wrote:
>> While I've intentionally made this as ugly (and self documenting) as
>> possible, I really have no idea how'd you'd clean this syntax up,
>> since I'm just not that familiar with D's introspection capabilites.
>> Does any one more familiar with D have a better way to implement
>> pattern matching?
> 
> I'd imagine patterns typically use constants, so you could at least do something like this:
> 
>     receive( test("p1 == \"foo\" || p2 == 5)( (string a, int b) {...} ) );
> 
> though this could still use a lot of improvement.

Guess you meant to close the quote like this:

receive( test("p1 == \"foo\" || p2 == 5")( (string a, int b) {...} ) );

But then again, what are we gaining compared to:

receive(
     bool(string a, int b) { if (a != "foo" && b != 5) return false; ...} );

?

I agree that a nicer pattern matching would be nice to have, but that's 
about it - "nice to have". It's not enabling.

That being said, it's worth looking into better ways of expressing 
matches, be they via current language mechanisms or new.


Andrei