On Mon, 01 Oct 2012 16:10:48 -0400, Tommi <tommitiss...@hotmail.com> wrote:
On Monday, 1 October 2012 at 18:36:23 UTC, Jonathan M Davis wrote:
CTFE was specifically designed with the idea that you would not need to
mark functions as CTFEable. You can call _any_ functio
at compile time. Some will fail, because they're doing things that CTFE
won't allow, but that's quickly caught, because it happens at compile
time. It completely avoids needing to mark
functions as CTFEable all over the place (which would generally
mean that functions wouldn't be CTFEable, because people would
frequently not mark them as CTFEable). constexpr is in direct
conflict with that design goal.
That's not what I suggested. I meant that all functions would still be
implicitly CTFEable by default, but an attribute like force_ctfe would
make it so that the function is guaranteed to execute at compile-time
when its arguments are compile-time constants.
And if you want a function to be executed at compile time, you assign
its result to an enum or static variable. Done. It's easy
and straightforward. I really don't understand why this is an
issue at all.
The issue to me is complicating the syntax of your code. The problem is
*having* to assign the result first to an enum, when I shouldn't have
to. I would like to be able to just say fun("times") and be confident
that that's going to be evaluated at compile-time. I feel like I've done
my part of the deal here, I provided the compile-time argument, and now
I'd expect the compiler to do his part and evaluate the function at
compile-time (if it has that force_ctfe attribute).
We already have that, use templates:
private auto _funimpl(string s) {
/* what was previously in fun(string) */
}
template fun(string s)
{
enum fun = _funimpl(s);
}
// usage:
fun!("times"); // always executes _funimpl at compile time
-Steve
