code review 148940044: spec: clarify scope and re-use of iteration variables

spec: clarify scope and re-use of iteration variables

Fixes issue 7834.

[gri, 2014-09-24 23:28:37]

Hello r, rsc, iant, ken2 (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[gri, 2014-09-24 23:30:01]

Hello r@golang.org, rsc@golang.org, iant@golang.org, ken@golang.org (cc:
golang-codereviews@googlegroups.com),

Please take another look.

[iant, 2014-09-25 00:21:26]

LGTM

[r, 2014-09-25 00:43:51]

https://codereview.appspot.com/148940044/diff/20001/doc/go_spec.html
File doc/go_spec.html (right):

https://codereview.appspot.com/148940044/diff/20001/doc/go_spec.html#newcode4681
doc/go_spec.html:4681: of the "for" statement; they are re-used in each
iteration.
should there be similar prose for if and switch?

[gri, 2014-09-25 04:13:50]

PTAL

https://codereview.appspot.com/148940044/diff/20001/doc/go_spec.html
File doc/go_spec.html (right):

https://codereview.appspot.com/148940044/diff/20001/doc/go_spec.html#newcode4681
doc/go_spec.html:4681: of the "for" statement; they are re-used in each
iteration.
On 2014/09/25 00:43:51, r wrote:
> should there be similar prose for if and switch?

Good point! The answer is no since the section on Declarations and Scope already
defines the scope for short variable declaration, and the section on Blocks
defines that if, switch, and for are in their own implicit block. So there's no
need to repeat scoping here.

Replaced this with one sentence about the variable re-use which is non-obvious.

For range clauses below it's slightly different because a) the form := range is
only _like_ a short variable declaration (and thus not covered elsewhere), and
the scope of the variables is only the for block (this was unclear before). For
instance, one cannot use an index variable declared by a range clause in the
range expression itself.

[rsc, 2014-09-25 19:10:13]

LGTM

[r, 2014-09-25 19:23:01]

LGTM

[gri, 2014-09-25 19:52:12]

*** Submitted as https://code.google.com/p/go/source/detail?r=10acb79292cc ***

spec: clarify scope and re-use of iteration variables

Fixes issue 7834.

LGTM=iant, rsc, r
R=r, rsc, iant, ken
CC=golang-codereviews
https://codereview.appspot.com/148940044