On Friday, 7 March 2014 at 01:15:43 UTC, Walter Bright wrote:
On 3/6/2014 4:43 PM, H. S. Teoh wrote:
What about using output ranges?
A great question. I tend to regard output ranges as suitable
for a container to expose. An algorithm reads an InputRange,
and presents its output as another InputRange. This is so that
algorithms can be easily chained together by the user, and the
last algorithm in the chain would be
std.algorithm.copy(OutputRange).
While I prefer this approach most of the time, I fear it has a
performance cost over sink-style algorithms (whether they use an
output range or build an array result). I guess the question is
whether this cost is generally offset by gains in the memory
allocation code or not.
For example, we could implement toStringz() as an algorithm
that looks like:
auto toStringz(S)(S s) {
return chain(s, repeat(0, 1))
}
std.range.only is more suitable than `repeat` here (and I don't
know if `chain` would let you chain a range of characters with a
range of integers):
auto toStringz(S)(S s)
if (is(Unqual!(ElementType!S) == dchar)) {
return s.chain('\0'.only());
}
Either way, perhaps the most serious problem is that when using
`copy` to write the result to an array, both UTF decoding and
re-encoding takes place (the result is always a range of `dchar`).
