On Saturday, 30 June 2012 at 14:22:06 UTC, Andrei Alexandrescu
wrote:
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).
Well, what about in the case of a BidirRange from a BDList?
Surelly, it would be defined by a start and finish point?
Take, on the other hand, creates a range, which is defined by a
start point, and a fixed length. Inserting elements into the
middle of the original list would bump elements out of the "take
range", which remains fixed sized.
On the other hand, had I manually shrunk my BDlistRange until it
was 5 elements long, and then inserted elements into the midle of
the list, it would cause my BDListRange to grow, and nothing to
drop out of it.
On Saturday, 30 June 2012 at 14:22:06 UTC, Andrei Alexandrescu
wrote:
On 6/30/12 8:24 AM, monarch_dodra wrote:
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
Well, if we forget Slist, and just focus on a standard
BidirectionalRange, say comming from a DList. Things don't really
get any better, because take still returns just a ForwardRange.
There is no way of doing, say:
BidirectionalRange aBD = ...;
//Create subrange...
//aBD = take(aBD, 5); //Error, wrong type
auto subrange = take(aBD, 5);
if(subrange.back == 5) //Error, subrange does not have a back
method.
//...But that's strange, because aBD IS a
bidiretinal range
Since the Take Range it is defined by a begining point and a
length, there is no way it could give Bidir access.
----
I came to D after reading your talk on ranges, and I really liked
(and am still enjoying) the concept. However, with C++, when you
iterate over [First, Last), you are also creating a two new
ranges: [First, Current) & [Current, Last). D doesn't provide
that, it only provides a way to shrink the current range and
create [Current, Last).
Using range, you don't get [First, Current). At best, you only get
a)A forward range only
b)A fixed size range
c)A range of another type
