On 1/21/11 3:15 PM, Tomek Sowiński wrote:
Jonathan M Davis napisał:
I don't know a terser way to get a full-fledged range. It comes at a cost,
though. Lazy parameters are just sugar over delegates, so it's not exactly
Usain Bolt**... And you can't return it because by bug or by design lazy
parameters (unlike vanilla delegates) don't work like closures. Still,
even with the overhead and limitations the idiom is remarkably useful,
especially in face of range-unfriendly libraries from outside D realm.
Enjoy.
What types of stuff do you need ad-hoc ranges for? What's the use case? I've
never actually needed such a thing. I'm curious. If it's really something that's
likely to be generally useful, then a function similar to what you're suggesting
probably should be added to std.range.
Like I said, anything that doesn't bother to expose range-interfaced iterators
and is not performance critical is considered a target for ad hoc ranges.
Working with non-D libraries, or libraries ported to D but preserving
mother-language idioms. Tasks like traversing a tree of GUI widgets, or
business specific objects where defining proper ranges rarely happens and is
use-case driven in practice. I expect they could be of some use in unittesting
as mock input. Vaguely related: educational -- ad hoc ranges read almost like a
for loop so the learning curve for ranges in general is eased off.
Adding them to Phobos is an interesting idea. We need to evaluate their worth,
though.
Everybody: if you could write up a one-liner like range(empty, popFront,
front), what would you use it for?
How about a singleton range - a range with exactly one element. It could
be done with repeat(x, 1) but let's try it with your function as a
warm-up exercise.
Andrei
