std.string.join & co. do a character-by-character copy because hasLength!string is false

[KennyTM~]

On May 28, 11 02:51, Vladimir Panteleev wrote:
> On Fri, 27 May 2011 21:29:10 +0300, KennyTM~ <kennytm at gmail.com> wrote:
>
>> On May 28, 11 02:05, Vladimir Panteleev wrote:
>>> Why hasLength!string is false:
>>> https://github.com/D-Programming-Language/phobos/blob/96941d5384a5fee302df/std/range.d#L767
>>>
>>>
>>>
>>> Would it make sense to introduce a hasOpaqueLength oslt. to fix this?
>>>
>>
>> You mean std.array.join? The 2-argument overload has specialization
>> for strings
>> (https://github.com/D-Programming-Language/phobos/blob/master/std/array.d#L966).
>>
>>
>> static if (isForwardRange!RoR && hasLength!RoR
>> && (hasLength!(ElementType!RoR) || isSomeString!(ElementType!RoR))
>> // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> && hasLength!R)
>>
>> It doesn't exist for the 1-argument overload though.
>
> Thanks! But it looks like the 2-argument overload is broken too. It
> doesn't check if the separator is a string, so that branch isn't taken
> for join(string[], string). In fact, it doesn't work at all when the
> second argument is an iterator with length:
>
> C:\Soft\dmd2\src\phobos\std\array.d(778): Error: template
> std.algorithm.copy(Range1,Range2) if (isInputRange!(Range1) &&
> isOutputRange!(Range2,ElementType!(Range1))) does not match any function
> template declaration
> C:\Soft\dmd2\src\phobos\std\array.d(778): Error: template
> std.algorithm.copy(Range1,Range2) if (isInputRange!(Range1) &&
> isOutputRange!(Range2,ElementType!(Range1))) cannot deduce template
> function from argument types !()(Result,string)
> test26.d(9): Error: template instance
> std.array.join!(string[],Map!(result,string)) error instantiating
>
> Program:
>
> import std.array;
> import std.algorithm;
>
> void main()
> {
> string[] arr;
> string sep;
>
> join(arr, map!"a"(sep));
> }
>
>

You're right. File a bug report?