On Wed, 29 Sep 2010 16:37:34 -0400, Andrei Alexandrescu
<[email protected]> wrote:
On 9/29/10 13:10 PDT, Jacob Carlborg wrote:
Would that be the uniform function call syntax that I've been waiting
for since I first heard of it?
Yah. One unpleasant issue I found with it (as it's already implemented
for arrays) is a chicken-and-egg thing: say I want to provide operation
moveFront only if the type doesn't define it yet. Without UCF (Uniform
Call Syntax) things are simple:
auto moveFront(R)(ref R r)
if (!is(typeof(r.moveFront())) && !hasElaborateCopy!(ElementType!R)) {
return r.front;
}
With UCF things get messy because introducing moveFront at global level
does make r.moveFront() legit, so the if clause returns true, which is
weird because the function shouldn't have been introduced yet. So the
compiler gets confused by this lying Cretan riddle - it recurses forever
(when R is an array).
The solution would be probably to not consider the symbol introduced
until the if-clause has cleared.
__traits(hasMember, r, "moveFront") && rest_of_expression_you_had
-Steve
