On Sunday, 25 September 2016 at 13:10:42 UTC, ZombineDev wrote:
But which opIndex and which length? Those of the container, or
those of the range? It doesn't make any sense to expect
container[].takeExactly(7).length to be different than 7. If
range.length returns the length of the container this would
break every sensible algorithm out there. How would you even
implement binary search
(https://rosettacode.org/wiki/Binary_search#D)? It's completely
wrong to expect indexing operations to work on the original
container. What you do in situations where there is no
container, such as generators (e.g. iota
https://github.com/dlang/phobos/blob/v2.071.2/std/range/package.d#L4722) and data coming from the network? And how would you get the number of remaining elements in the range?
The argument is not that the length of a range should always
evaluate to the length of some container it enumerates, but that
the length of the range should not change based on your position
in the range. In phobos, popFront effectively reduces the length
of the range by one, and offsets all further calls to opIndex and
opSlice. I expect length, opIndex, and opSlice to behave the same
whether I just built the range, am halfway through the range, or
have fully consumed the range.
Phobos' range facilities vomit when you try to deal with
static arrays, and they have to be coerced into dynamic arrays
before they can be dealt with. This is silly.
What's the problem here? Just slice them using the [] syntax
(i.e. the analog of asrange in your library).
As Jonathan pointed out there's a lot of muddying of how dynamic
arrays are only sorta-kinda genuine arrays. But when using them
one should be able to rely on dynamic and static arrays have the
same interface, except that one can be resized and appended to
and another cannot. Having to slice static arrays to pass them
into phobos' HOFs is icky and completely unnecessary. And though
you might say that you could just append `[]` to every array you
pass in, but while it will work for static and dynamic arrays it
won't work for everything that can be passed to a function
accepting a range.
Consistency of syntax for performing the same operation upon many
different types is not to be undervalued.
