RE: RFC 360 (v1) Allow multiply matched groups in regexes to return a listref of all matches

On Sunday, October 01, 2000 1:38 AM, Perl6 RFC Librarian 
[SMTP:[email protected]] wrote:
> This and other RFCs are available on the web at
>   http://dev.perl.org/rfc/
>
> =head1 TITLE
>
> Allow multiply matched groups in regexes to return a listref of all matches
>
> =head1 VERSION
>
>   Maintainer: Kevin Walker <[email protected]>
>   Date: 30 Sep 2000
>   Mailing List: [email protected]
>   Number: 360
>   Version: 1
>   Status: Developing
>
> =head1 DESCRIPTION
>
> Since the October 1 RFC deadline is nigh, this will be pretty informal.
>
> Suppose you want to parse text with looks like:
>
>      name: John Abajace
>      children: Tom, Dick, Harry
>      favorite colors: red, green, blue
>
>      name: I. J. Reilly
>      children: Jane, Gertrude
>      favorite colors: black, white
>
>      ...
>
> Currently, this takes two passes:
>
>      while ($text =~ /name:\s*(.*?)\n\s*
>      					children:\s*(.*?)\n\s*
>      					favorite\ colors:\s*(.*?)\n/sigx) {
>          # now second pass for $2 ( = "Tom, Dick, Harry") and $3, yielding
>          # list of children and favorite colors
>      }
>
> If we introduce a new construction, (?@ ... ), which means "spit out a
> list ref of all matches, not just the last match", then this could be
> done in one pass:
>
>      while ($text =~ /name:\s*(.*?)\n\s*
>      					children:\s*(?:(?@\S+)[, ]*)*\n\s*
>      					favorite\ colors:\s*(?:(?@\S+)[, ]*)*\n/sigx) {
>          # now we have:
>          #  $1 = "John Abajace";
>          #  $2 = ["Tom", "Dick", "Harry"]
>          #  $3 = ["red", "green", "blue"]
>      }
>
> Although the above example is contrived, I have very often felt the need
> for this feature in real-world projects.
>
> =head1 IMPLEMENTATION
>
> Unknown.
>
> =head1 REFERENCES
>
> None.
>
>
> --
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Definitely. I think this has been one of the few actual "flaws" in the 
language. People are always trying to

($part1, $somevar) =~ s/(.*):(.*)/;

This would be in list context. In scalar context, it could still grab the 
number of patterns matched in the parenths, or a 1|0 to indicate a match at 
all, which would be less useful. Since it's a common error (I believe it's even 
FAQed a few times), the request goes well beyond a request for syntactic sugar, 
and points out a flaw in the language. People expect it to be there as a part 
of what makes Perl make sense.