Next Generation Regexp

prostoalex writes "Jeffrey E. F. Friedl, author of newly published 2nd edition of Mastering Regular Expressions, wrote a feature article for O'Reilly Network on the recent innovations in the regular expression world. You'd think that such area as regular expressions would be fairly stable, but according to the author, 'when I started to work on the second edition of Mastering Regular Expressions and started refocusing on the field, I was rather shocked to find out how much had really changed'. The article's behind-the-scene purpose is apparently to push a new book that O'Reilly published this month, but it has great educational value for anyone involved with practical extracting and reporting."

Comments

what about perl 6?

[jbennetto]

He doesn't even mention the radical changes to regexps in Perl 6, as described in the recent Apocalypse 5 and Synopsis 5.

at some point...

[g4dget]

Beyond a certain degree of complexity, it really doesn't make much sense anymore to use regular expressions--a simple built-in parser generator with executable annotations is both clearer and more powerful. Parser generator syntax allows comments, whitespace, with a simple, fairly standard syntax.

Perl and other languages should leave "good enough" alone when it comes to regular expressions and instead just make it easy to put chunks of grammars into programs.

Re:regexp are way overrated

[Anthony Boyd]

Text processing - why isn't your text marked up?

While you later concede that form input and input from other programs might be good reasons to use a regex, that you would even pose this question is strange. For 90% of the regex fans, form input and screen scraping is exactly what they do. For almost any Web developer, this is the day-in, day-out norm. So your point seems to downplay the very uses that have made regex's so popular.

I've ecountered many regexpr's for email addresses, all of them work on your bog standard address, none of them work when deployed

You realize this does not bolster your claim that regex's are "overrated" -- it merely points out that some developers are overrated. A bad developer does not make a language bad.

That HTML tag stripper you hacked up, did you remember to handle comments?

Same as above. You're complaining about human error and then blaming the regex system itself.

I've just come to associate use of regular expressions with flakey or hastily written software.

Of course. But the hastily written software is the other software we interact with, not our own. And that's a broad generalization for many developers, so of course you can find exceptions. But you asked for other people's views, and in my view, regex's are sorely needed -- not so bad developers can stay bad, but so that the good developers can clean up the messes left behind after the bad developers go. It's a nice bonus that good regex developers can pull in hostile data, screen scrape, and cleanse form input. That helped one of my employees get a raise last quarter.