[phobos] bug in map

Dmitry Olshansky dmitry.olsh at gmail.com
Fri Aug 17 02:14:18 PDT 2012

On 06-Aug-12 22:55, Andrei Alexandrescu wrote:
> Consider:
> auto s = "some string";
> static assert(!hasLength(typeof(s));
> auto m = map!(a => a)(s);
> static assert(!hasLength(typeof(s));
> Both asserts should pass: string famously has a length that's actually 
> not the length of the range. Then mapping something on top of the 
> string should also have no meaningful length. Alas, it does, because 
> of the following code in std.algorithm:
> static if (hasLength!R || isSomeString!R)
> {
>     @property auto length()
>     {
>          return _input.length;
>     }
>     alias length opDollar;
> }
> The code used to introduce length only if if (hasLength!R).
> It seems Kenji introduced this change. What was its purpose, and can 
> we undo it? This breaks the entire web of 
It bugs me  - the indecision on this matter. No Kenji didn't introduce it.

The guilty commit (that could be reverted on it's own):

SHA-1: d0457fe82a5f140218d8a9700eb7c26a236d4abe

* This test is actually needed

Adds "isSomeString" to map's "length" test.
Author: monarchdodra

Contains one line diff that goes as follows:
-static if (hasLength!R)
+static if (hasLength!R || isSomeString!R)

P.S. I do not suggest to gill our new contributors but to pay more 
attention during the review of pulls.

Olshansky Dmitry

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