On Sat, 11 Jun 2011 09:25:19 -0400, Michel Fortin
<michel.for...@michelf.com> wrote:
On 2011-06-11 09:05:52 -0400, "Steven Schveighoffer"
<schvei...@yahoo.com> said:
As far as the negation, I think we need one more layer of type:
struct FlagParam(string pname)
{
Flag!pname value;
alias value this;
this(Flag!pname x) { this.value = x }
FlagParam op???() const { return FlagParam(cast(Flag!pname)!value);
}
}
BTW, is there a way to hook "!"? Maybe this won't work... The idea
is to have Yes.abc return FlagParam!"abc"(Flag!"abc".yes).
If you need to convert a bool to a Flag!"abc", you can do any of these:
func(expression ? Yes.abc : No.abc);
or
func(cast(Flag!"abc")expression);
or, with your proposal:
func(FlagParam!"abc"(expression));
None of this is very appealing, but I find the first is the most
readable.
We need another struct besides Yes and No that allows creation with
another opDispatch:
Foo.abc(expression);
The best name for Foo is Flag, but that's taken...
But still, is there a way to override the type returned by !flag? I think
there isn't... That's kind of sucky. Flipping of a flag is a very common
feature, I would expect to be able to do it easily.
Hm... what if opCast!bool() returns something other than bool? does that
actually work? That *would* be a hack :)
We could also possibly use unary - to denote flipping a flag. That's very
hacky too, but I think it would work.
-Steve
