Am 26.08.2012 20:07, schrieb Jonathan M Davis:
On Sunday, August 26, 2012 10:17:13 Jonathan M Davis wrote:
On Sunday, August 26, 2012 17:41:45 David wrote:
It's a RefRange, but not completly ... Can somebody explain me that
behaviour?
http://dpaste.dzfl.pl/643de2a3
refRange simply returns the original range if it's an input range rather
than a forward range, since normally, when you have an input range, it
isn't a value type, and there's no way to copy it, so operating on one
reference of it is already the same as operating on all of them, making
RefRange pointless.
However, you've done the odd thing of declaring a value type input range. I
don't know why that would ever be done except through ignorance of how
ranges work. So, refRange is actually returning a copy in your case, which
is why you're having problems.
Though the fact that you ran into this issue may indicate that having refRange
return the original if it isn't a forward range was a bad decision. I don't
know. In the normal case, it's definitely better, because it avoids an
unnecessary wrapper, but obviously, people can make mistakes. You should still
be able use RefRange with an input range though, as long as you use it
directly.
auto wrapped = RefRange!TestRange(&orig);
But it would be better IMHO to just fix it so that your range is a forward
range, since there's no reason for it not to be.
- Jonathan M Davis
Ranges died another time for me. This refRange copy thingy cost me lots
of time, then I tried to implement a .save method, which uhm, just
didn't work together with RefRange (isForwardRange!T succeeded, but
isForwardRange!(RefRange!T) failed).
Anyways, thanks for your explanations!
