On Tue, 12 Jul 2011 00:01:55 +0300, Jonathan M Davis <jmdavisp...@gmx.com>
wrote:
The solution is to fix template instantiation so that it's smarter when
dealing with static arrays and const or immutable arrays:
http://d.puremagic.com/issues/show_bug.cgi?id=6148
It's a language issue, not a design issue. Making ranges function like
slists
(with head and tail or car and cdr) would be almost certainly be too
inefficient (particularly for ranges where save is not super cheap,
though
it's at least supposed to be fairly cheap). Immutability might be nice,
but it
does have its costs, and in this case, D's templates aren't currenly
smart
enough to use immutable(E)[] instead of immutable(E[]). And it's not like
immutable ranges are going to work with non-array ranges anyway, so it's
arguably a good idea to just expect immutable and const ranges to not
work
anyway.
There is a simple workaround for this type of ranges that are like
iterators, which we know the beginning and the end.
We can improve isForwardRange!R by adding a line hasForwardRange!R. If it
does have, we return an adaptor which gives us a mutable range.
Good thing is because the original range is mutable we don't need to worry
about anything else.
