Am Thu, 12 Dec 2013 08:43:35 -0800
schrieb "H. S. Teoh" <hst...@quickfur.ath.cx>:
> I do this with my own ranges sometimes. Sometimes, it's more performant
> to precompute the value of .front and store it (as .front), and have
> .popFront compute the next value, than to have .front compute the value
> every time. AFAICT, this is perfectly fine and should work with Phobos
> seamlessly. The power of ducktyping!
>
>
> T
Most non-trivial ranges do the actual work in `popFront()' and
return a cached value from `front'. It has been argued as a
design quirk, that this in general leads to:
struct Range
{
bool popFrontHasBeenCalledOnce = false;
T current;
@property T front()
{
if (!popFrontHasBeenCalledOnce)
{
popFront(); // initializes `current'
}
return current;
}
[…]
}
--
Marco
