On Mon, 06 May 2013 17:13:00 -0400, Idan Arye <generic...@gmail.com> wrote:
On Monday, 6 May 2013 at 19:47:33 UTC, Diggory wrote:
It's a nice idea but personally I don't like the syntax much, for
example it's completely non-obvious what "true" does when passed to the
singleton mixin, or that the parameters to the property mixin are
"type, name, condition, initial value".
I suppose you could do something like this:
mixin property!`int x = 1`;
The other problem is that I don't think it's beneficial to invite the
use of mixins for such simple substitutions. I'd rather see the
majority of code be standard D syntax, and the use of mixins be the
exception rather than the rule. It's similar to how excessive use of
macros in C++ is generally considered bad practice.
If D supported Java's annotation metaprogramming I could have
implemented a syntax like:
@Property(`a < 50`) int a = 1;
since it doesn't, I have to use mixin templates...
D supports @Property syntax (though I would suggest a different
identifier) via User-defined-attributes. However, you will still need the
mixin, I don't think it can add code.
This brings up a good idiom though. Since mixin is the only thing that
can inject code, but its usage is ugly, @uda's can be useful for
specifying nice parameters to the mixin, and you could have one mixin per
class instead of per property. I think Manu uses this to great effect
(was in his first talk).
-Steve
