On 2010-10-16 17:45:56 -0400, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> said:
unittest
{
auto x = new Drawable;
auto a = nameone!Widget(x); // works
//auto b = nameone!ColoredWidget(x); // doesn't compile
auto c = nametwo!ColoredWidget(x);
c.draw(); // works
c.setColor(red); // throws NotImplemented during runtime
}
"nameone" implements Kenji's current code. "nametwo" is the looser form
of duck typing: whatever methods match will work, and the rest are
implemented to throw during runtime.
What you're proposing above is just useless, and I'm honestly quite
surprised you don't realize that.
The real duck type almost already exists in Phobos, and it's called a
variant. The only problem with it is that it is powerless when it comes
to calling functions without casting it's content to a type first. Make
it so this code can run and then you'll have implemented duck typing
for real:
class Duck { void quack(); }
Variant v = new Duck;
v.quack();
Well, mostly. It could also be argued that this too should work too:
Variant v = cast(Object)(new Duck);
v.quack();
but that'd require runtime reflexion as part of ClassInfo.
--
Michel Fortin
michel.for...@michelf.com
http://michelf.com/
