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Re: [PATCH] Do not allow identifiers that start with a negative number.
From: |
Joel E. Denny |
Subject: |
Re: [PATCH] Do not allow identifiers that start with a negative number. |
Date: |
Mon, 24 Jan 2011 22:47:02 -0500 (EST) |
User-agent: |
Alpine 2.00 (DEB 1167 2008-08-23) |
Hi,
On Wed, 19 Jan 2011, Paul Eggert wrote:
> On 01/19/2011 12:13 AM, Alex Rozenman wrote:
> > it is impossible to obtain an unambiguous grammar with syntax extensions
> > like id '[' c_id ']' without involving the ';' requirement.
>
> Yes, but that's OK; that's what I'm proposing. That is, I'm proposing that
> if a user wants to use the new syntax extensions, the user also must put ';'
> at the end of each rule.
>
> It's OK to require ';' for new grammars. Omitting ';' has been deprecated
> for many years, and no new grammars should be omitting ';'.
I also agree that the code here is hard to read and that something should
be done eventually. However, unless there's a bug, can we postpone this
work until after the 2.5 release? Named references are experimental, and
omitting semicolons is deprecated, so I don't see any pressing need to
address this now. I feel it would be more beneficial to spend our scarce
time on the problems already raised in this thread.
Also, as you probably recall, the reason scan-gram.l has to be so messy in
order to support omitting semicolons is because Bison-generated parsers
support only one token of lookahead. However, after 2.5, I'd like to
propose a mechanism that enables a user to cleanly extend lookahead at
particular points in a grammar. About a year ago, I implemented that
mechanism offline and successfully used it to clean up this area of the
grammar without changing the functionality. So, whenever we return to
this issue, if we find that there's no other nice way to clean up this
code without losing important backward compatibility, we'll still have a
decent way out.
- Re: [PATCH] Do not allow identifiers that start with a negative number., (continued)
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/08
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/08
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/09
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/10
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/15
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/15
- Re: [PATCH] Do not allow identifiers that start with a negative number., Alex Rozenman, 2011/01/16
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/18
- Re: [PATCH] Do not allow identifiers that start with a negative number., Alex Rozenman, 2011/01/19
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/20
- Re: [PATCH] Do not allow identifiers that start with a negative number.,
Joel E. Denny <=
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/25
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/25
- Re: [PATCH] Do not allow identifiers that start with a negative number., Paul Eggert, 2011/01/25
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/25
- Re: [PATCH] Do not allow identifiers that start with a negative number., Akim Demaille, 2011/01/26
- Re: [PATCH] Do not allow identifiers that start with a negative number., Akim Demaille, 2011/01/26
- Re: [PATCH] Do not allow identifiers that start with a negative number., Akim Demaille, 2011/01/26
- Re: [PATCH] Do not allow identifiers that start with a negative number., Akim Demaille, 2011/01/26
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/27
- Re: [PATCH] Do not allow identifiers that start with a negative number., Joel E. Denny, 2011/01/29