code review 5688074: go spec: import path implementation restriction

go spec: import path implementation restriction

[gri, 2012-02-22 21:34:51]

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

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

[r, 2012-02-22 21:41:30]

http://codereview.appspot.com/5688074/diff/4002/doc/go_spec.html
File doc/go_spec.html (right):

http://codereview.appspot.com/5688074/diff/4002/doc/go_spec.html#newcode5102
doc/go_spec.html:5102: following characters:
the replacement char too.

[r2, 2012-02-22 21:43:56]

shouldn't the definition be permissive rather than rejective?

any legally utf-8-encoded printable unicode char, as defined by XXX, with the
exception of
the ascii frog list
spaces
FFFD if it's printable (not sure)

[gri, 2012-02-22 22:00:54]

PTAL.
Added replacement char.

On Wed, Feb 22, 2012 at 1:43 PM, Rob 'Commander' Pike <r@google.com> wrote:
> shouldn't the definition be permissive rather than rejective?

Not sure. For one, "printable" seems less clearly defined that this
list (which corresponds exactly to what is implemented), and it's a
restriction, so "reject" seems fitting.

I'll try to change it if you feel strongly about it.
- gri

>
> any legally utf-8-encoded printable unicode char, as defined by XXX, with the
exception of
> the ascii frog list
> spaces
> FFFD if it's printable (not sure)
>

[rsc, 2012-02-22 22:07:09]

I think rejective is okay: I intended to allow nearly everything
except problematic ASCII characters.  On that note I think
we have to allow ~, which I believe gets used in launchpad.net
import paths today.

Russ

[gri, 2012-02-22 22:11:04]

PTAL

(Also updated: http://codereview.appspot.com/5683077)

On Wed, Feb 22, 2012 at 2:07 PM, Russ Cox <rsc@golang.org> wrote:
> I think rejective is okay: I intended to allow nearly everything
> except problematic ASCII characters.  On that note I think
> we have to allow ~, which I believe gets used in launchpad.net
> import paths today.
>
> Russ

[r2, 2012-02-22 23:46:18]

for the discussion so far, the code is fine, but i believe it's a mistake to
allow non-printable characters in a path, and it's very easy to define what
printable means, just as easy as to define what space means.

in short, i still prefer my form

-rob

[adg, 2012-02-23 00:10:41]

On 23 February 2012 10:46, Rob 'Commander' Pike <r@google.com> wrote:
> for the discussion so far, the code is fine, but i believe it's a mistake to
allow non-printable characters in a path, and it's very easy to define what
printable means, just as easy as to define what space means.
>
> in short, i still prefer my form

I also prefer to provide a list of acceptable characters. Something we
haven't anticipated may bite us later.

[rsc, 2012-02-23 03:07:03]

Implementation restriction: A compiler may restict ImportPaths to be
non-empty strings using only Unicode's L, M, N, P, and S categories
(the definition of Graphic, without spaces)
and may also exclude the ASCII characters
<code>!"#$%&amp;'()*,:;&lt;=&gt;?[\]^`{|}</code>.

[gri, 2012-02-23 07:20:06]

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

Please take another look.

[r, 2012-02-23 07:48:12]

LGTM

[gri, 2012-02-23 07:51:27]

*** Submitted as http://code.google.com/p/go/source/detail?r=eb997f446b2e ***

go spec: import path implementation restriction

R=rsc, r, r, adg
CC=golang-dev
http://codereview.appspot.com/5688074