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Postings from February 2012
On Mon, Feb 6, 2012 at 9:23 PM, demerphq <demerphq@gmail.com> wrote: > Ah, I see, this is a misunderstanding. "match and substitution > operator flags", to me reads quite differently to your original words > "match substitute operator flags". oops, typo! > > Perl gives errors when you use "g" and "c" as regex flags. > > Here you seem to use "regex flags" where I would say "pattern > compilation (constructor) flags". Noted. And yes of course Perl complains > when you use a modifier which controls how the match is performed on a > pattern constructor which does not actually do any matching. > That's good. That's what I would expect. The problem is that perlre lumps "g", "c" and "p" into the documentation for regex pattern compilation flags. I find the term "regex flags" to be ambiguous and "Regex pattern > flags" to only be marginally better. Some of the terms I have used > elsewhere in this thread are equally bad. Since this ambiguity seems > to lead to confusion, lets try to come up with better terms. :-) > perlre simply calls them "modifiers" and "flags modifiers". The re pragma calls them "flags" and "modifiers". It could definitely be improved. --------------------------------------------- > 1. Pattern semantics flags: /m /i /s /u /d /l /a > > These modifiers change the meaning of specific meta-character, or > literal text. These apply to qr//, m// and s/// > > 2. Pattern compilation flags: /x /o > > These patterns change the process by which a pattern is compiled. /x > does so by causing the regex compiler to ignore specific parts of the > pattern passed in, and /o by determining how often it gets compiled. > These apply to qr//, m// and s/// > > 3. Match control flags: /g /c > > These control how the matching is to proceed, and only apply to m// and > s///. > > 4. Substitutions flags: /e /r > > These control the behavior of the substitution operator, and apply only to > s/// > > --------------------------------------------- > > Unfortunately this leaves /p out Sounds good. A few comment/nits: I'm not sure a distinction is needed between (1) and (2), and it will lead to having to the following mouthful: "(?:) accepts pattern semantic flags and pattern compilation flags". perlop lists /ee in addition to /e, so /ee should be listed explicitly here. Because of where it can be used, I'd place /p under (2). (I believe it should be in (3), but that's not how it was implemented.) - EricThread Previous | Thread Next