On 6/30/12 8:24 AM, monarch_dodra wrote:
On Saturday, 30 June 2012 at 11:35:07 UTC, Tobias Pankrath wrote:
std.algorithm.take.
But I would generally avoid SList.
Thanks, but isn't that kind of a crutch solution?
I mean:
1) It creates a new type, so any attempt to use it to modify an existing
range becomes impossible:
void main()
{
SList!int slist;
foreach(i; iota(5,0,-1))
slist.insertFront(i);
sr1 = take(sr1, 2); //Nope, not gonna happen
writeln(sr1);
}
One can't expect that to happen more than suspending a law of physics.
The state needed for iterating an entire slist is a pointer. The state
needed for iterating at most n elements of an slist is a pointer plus
and integer. They're just different notions.
2) The new range is defined as a fixed length from the beginning of the
range, as opposed to start and finish points. If I were to insert new
items into my Slist, the new range would just bump the top items out of
its range.
SList's range is not defined by start and finish points. It's defined as
the start point, and the finish point is implicit by use of a sentinel
(the null pointer).
3) This doesn't work for BidirectionalRanges: The resulting range is
forward only. For the same reason, it is not possible to have a TakeLast
for bidirectional ranges.
Not sure I understand this, but when we get into the realm of bidir
ranges, things get a fair amount better. How would TakeLast work?
Andrei
