Re: [Boost-users] [regex] - bk_parens and bk_braces missingfrom1.33.x

From: John Maddock (john_at_[hidden])
Date: 2006-02-12 05:09:19

> Yes, but because they could previously be individually selected, I
> gave the users of my application the option of setting bk_parens
> and/or bk_braces, separately from choosing POSIX or Perl semantics. It 
> seems that syntax and semantics are no longer orthogonal.  I don't
> have strong feelings about that, but just wanted to check that it was
> intentional, before hacking the application.

OK understood, but if you use Basic-style syntax with Perl like extensions 
you can get into trouble particularly if you try and match non-greedy 
repeats POSIX style.  So, I guess what I'm saying is it avoid a whole lot of 
confusion all round if you stick to one of the standard syntaxes or their 
variations:  basic, extended, perl, emacs etc.  My guess is your users would 
find it less confusing as well - most people (all of them?) would want 
regexes that follow whatever form they've used before, rather than inventing 
their own new syntax.

You can still choose whether to use Perl-style matching or POSIX-style 
leftmost longest matching independently of the syntax type, but I'd recomend 
that you don't, or at least that you don't try and use Perl syntax with 
leftmost-longest rules. The other way around however: POSIX syntax with Perl 
matching rules is OK (and is more or less what emacs does).

John.