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Re: Emacs regexp scan (Sep 29)

From: Paul Eggert
Subject: Re: Emacs regexp scan (Sep 29)
Date: Sat, 5 Oct 2019 02:52:34 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0

On 10/5/19 1:10 AM, Eli Zaretskii wrote:
both variants are valid, so it sounds like your personal stylistic
preference is for the latter.  Is that the only reason?

No. The "Special Characters in Regular Expressions" subsubsection of the Elisp manual recommends putting '-' at the end of bracket expressions, since putting '-' elsewhere can cause confusion (one or two examples of which caused bugs that was fixed in that patch). The patch did not systematically put "-" at the end of every bracket expression, only those reasonably near bugs and other glitches.

If the regexp scanner needs to be pacified, isn't it better to fix the
scanner instead?

No, as the regexp scanner was right here: it complained about unescaped literal "+" in regexps, which is poor practice (and is documented as poor practice in the Elisp manual).

original code looks simpler to me than the new one, as the former is
just a simple while loop, whereas the latter is a nested dolist.

Actually the old code was so confusing that it was a bit hard to see that it was a nested loop (not a simple while loop). I originally had the same confusion that you did, which is why I redid the loops to make the nesting more obvious and to lessen the number of lines of code.

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