From: ahoward <ahoward@...>
Date: 2003-04-08T01:28:47+09:00
Subject: Re: ruby-dev summary  19944 - 19957

On Tue, 8 Apr 2003, Brian Candler wrote:

> On Tue, Apr 08, 2003 at 12:20:40AM +0900, Kazuo Saito wrote:
> > They plan to change the regexp parsing rule in 1.8.0 as follows so far.
> > The plan is based on regexp coding conventions and requests from others
> > in ruby-dev:
> ..
> > 2) A literal '-' in a character class should be escaped too if the
> >    class has other '-' literals for range representation.  For instance,
> >    /[abcd-f-hijk]/ and /[--abc]/ should be written as
> >    /[abcd-f\-hijk]/ (or /[abcd\-f-hijk]/) and /[\--abc]/.
> >    You can use '-' without '\' if the class has no ranges, like
> >    /[-abc]/ or /[^-]/.
>
> The way I parse regexps in my brain is the way I have been conditioned
> through what I have learned with grep, awk, perl and so on :-)
>
> I often use character classes like this:
>
>      /[a-zA-Z0-9.-]/
>
> which matches a-z, A-Z, 0-9, dot or dash. This is how it works everywhere
> else. The rule is 'if you want to match a dash, put it at the very beginning
> or very end of your character class'
>
> I can't see any particular reason to outlaw this practice...

i'm with brian on this - those of us who've been converting old lex/perl
parsers to ruby have enough trouble saving the regexes people took hours to
write.  backward compatibility in something as arcane as regexes is not just
nice - it's essential.

-a

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