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Postings from September 2021
Hi all,
I brought this up on PCRE2 (at
<https://github.com/PhilipHazel/pcre2/issues/15>), but the author
rightfully pointed out that it's something Perl doesn't do.
1. The (minor) problem is that a regular expression cannot begin
directly with a naming group, it must be parenthesised. This makes
expressions that use named patterns produce result sets that are 1
item longer than necessary, and contain a duplicate member (0 and
1). It is more pronounced when using the "g" modifier, because
iterating the matches then has multiple 0 groups that cannot be
addressed using a semantic name.
2. The proposed syntax is to allow a pattern like
/?<name>.../
rather than requiring
/(?<name>...)/
3. The benefits are consistent semantic access of match result members,
and smaller result sets. I'm sure results are already
memory-efficient with named and numbered groups pointing to the same
data, but they have more output when examined or used.
4. From basic testing with PCRE, expressions that begin with ? fail to
compile, but I'm not certain that's the case for all regexp usage in
Perl. It looks like a backwards-compatible change.
Regards,
Roy.
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