code review 7135058: spec: clarify lhs syntax for range and select

spec: clarify lhs syntax for range and select

Fixes issue 4653.

[gri, 2013-01-18 20:12:07]

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

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

[thakis, 2013-01-18 20:14:04]

Thanks!

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html
File doc/go_spec.html (right):

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html#newcode4559
doc/go_spec.html:4559: The receive case may declare one or two new variables
using a
s/one or two// here?

 a, b, c, d := f_returning_4_tuple()

is syntactically valid after this cl.

[gri, 2013-01-18 20:20:09]

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html
File doc/go_spec.html (right):

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html#newcode4559
doc/go_spec.html:4559: The receive case may declare one or two new variables
using a
On 2013/01/18 20:14:04, thakis wrote:
> s/one or two// here?
> 
>  a, b, c, d := f_returning_4_tuple()
> 
> is syntactically valid after this cl.

It can only be one or two. This CL simply trades some accuracy for some other:
Now the syntax permits arbitrary long lists on the lhs, but it makes it clear
that the lhs has to identifiers if we have a := .

But in both cases (range, select) we have additional prose restricting to one or
two lhs operands, so that's fine.

Finally, the syntax in this document often is "liberal" for brevity; the prose
is important.

[thakis, 2013-01-18 20:21:50]

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html
File doc/go_spec.html (right):

https://codereview.appspot.com/7135058/diff/2001/doc/go_spec.html#newcode4559
doc/go_spec.html:4559: The receive case may declare one or two new variables
using a
On 2013/01/18 20:20:09, gri wrote:
> On 2013/01/18 20:14:04, thakis wrote:
> > s/one or two// here?
> > 
> >  a, b, c, d := f_returning_4_tuple()
> > 
> > is syntactically valid after this cl.
> 
> It can only be one or two. This CL simply trades some accuracy for some other:
> Now the syntax permits arbitrary long lists on the lhs, but it makes it clear
> that the lhs has to identifiers if we have a := .
> 
> But in both cases (range, select) we have additional prose restricting to one
or
> two lhs operands, so that's fine.
> 
> Finally, the syntax in this document often is "liberal" for brevity; the prose
> is important.

Makes sense, thanks.

[rsc, 2013-01-18 21:17:11]

LGTM

[gri, 2013-01-18 21:59:49]

*** Submitted as https://code.google.com/p/go/source/detail?r=ef1ce4503d85 ***

spec: clarify lhs syntax for range and select

Fixes issue 4653.

R=rsc, r, iant, ken, thakis
CC=golang-dev
https://codereview.appspot.com/7135058