[Issue 4707] auto ref for foreach loops

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4707


monarchdodra at gmail.com changed:

           What    |Removed                     |Added
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                 CC|                            |monarchdodra at gmail.com


--- Comment #5 from monarchdodra at gmail.com 2013-11-02 03:10:11 PDT ---
(In reply to comment #4)
> This is still an interesting proposal.

Seconded. Thoguh I do seem to remember that another Bug Report about this was
open... I did find this interesting thread about it though:
http://forum.dlang.org/thread/ceftaiklanejfhodbpix@forum.dlang.org

This proposal has 2 very important (IMO) ramifications:
First, it would allow making "foreach(ref; range)" illegal, if said range
doesn't give ref access. This is a *big* source of bugs.

Second, once we have this, we would be able to write *correct* generic code.
Read this extract from "reduce":
            // For now, just iterate using ref to avoid unnecessary copying.
            // When Bug 2443 is fixed, this may need to change.
            foreach (ref elem; r)
            {

Or "I'm doing wrong, but it seems to work".

So long story short, if we ever hope to have "ref-correct" foreach, we *must*
have "auto ref" to make foreach useable in generic code.

This gets a vote from me

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