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Re: Discrepancy in definition/use of match-data?
From: |
Richard Stallman |
Subject: |
Re: Discrepancy in definition/use of match-data? |
Date: |
Fri, 11 Jun 2004 21:51:06 -0400 |
Now the obvious solution to that would be to make unsuccessful
matches void the match-data, too.
That might be a good thing to do, except that doing it now is likely
to delay the release.
So my proposal is the following plan:
Before next release:
match-data gets voided upon entry of a filter or sentinel, like it is
being done now. With void match-data, match-beginning and so on flag
an error irrespective of their argument. The match-data is only
touched by a successful match. Once a match has been successful,
match-beginning and so on will not flag errors for positive
arguments, but return nil (as documented).
In order to have a better chance of catching such
use-before-valid-match situations, it might be a good idea also to
void the match-data in the main loop.
Voiding in the main loop was exactly the idea that occurred to me.
So let's do all of this now.
After the next release, I would like to have unsuccessful matches
also void the match-data, making the use of the above quoted idiom
illegal.
I agree. (But please, let's say "cause an error", not "illegal".
Nobody is going to be jailed for doing this.)
We should do this change right after the next release so that Emacs
core developers and those for add-on packages have enough time testing
it, finding the problematic code and fixing it for the next release
after that.
We could do it right now in the Unicode branch. That way, we'd assure
it will get into the following major release, but detection of code
that needs changing could start right away.
- Re: Discrepancy in definition/use of match-data?, (continued)
- Re: Discrepancy in definition/use of match-data?, Stephen J. Turnbull, 2004/06/12
- Re: Discrepancy in definition/use of match-data?, David Kastrup, 2004/06/12
- Re: Discrepancy in definition/use of match-data?, Richard Stallman, 2004/06/12
- Re: Discrepancy in definition/use of match-data?, Stephen J. Turnbull, 2004/06/14
- Re: Discrepancy in definition/use of match-data?, David Kastrup, 2004/06/14
- Re: Discrepancy in definition/use of match-data?, Stephen J. Turnbull, 2004/06/14
- Re: Discrepancy in definition/use of match-data?, Stephen J. Turnbull, 2004/06/16
- Re: Discrepancy in definition/use of match-data?, Richard Stallman, 2004/06/18
- Re: Discrepancy in definition/use of match-data?, Richard Stallman, 2004/06/18
- Re: Discrepancy in definition/use of match-data?, Stephen J. Turnbull, 2004/06/23
- Re: Discrepancy in definition/use of match-data?,
Richard Stallman <=