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This queue is for tickets about the Regexp-Grammars CPAN distribution.

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The Basics
Id: 61459
Status: open
Priority: 0/
Queue: Regexp-Grammars

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Owner: Nobody in particular
Requestors: ARODLAND [...] cpan.org
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Subject: Warn about nonreentrant regex engine in the caveats section of POD
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This is kind of funny since I'm the one who wrote you asking to have objrule call the class constructor properly, but anyway... I think it would be worth noting in the IMPORTANT CONSTRAINTS AND LIMITATIONS section of the POD that the perl5 regex engine is (so far) non-reentrant -- any code that triggers a regex match inside of (?{ ... }) or (??{ ... }) will lead to weird data corruption and most likely segfaults. In particular this means constructors called by <objrule:>, and in very particular it means Moose constructors under many conditions, like having an attribute with an 'Int' type constraint. Thanks, Andrew
Subject: Re: [rt.cpan.org #61459] Warn about nonreentrant regex engine in the caveats section of POD
Date: Mon, 20 Sep 2010 07:50:02 +1000
To: bug-Regexp-Grammars [...] rt.cpan.org
From: Damian Conway <damian [...] conway.org>
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Thanks, Andrew. I have now adapted your wording to add the following warning at the very top of the "IMPORTANT CONSTRAINTS AND LIMITATIONS" section: The Perl 5 regex engine is not reentrant. So any attempt to perform a regex match inside a C<(?{ ... })> or C<(??{ ... })> will almost certainly lead to either weird data corruption or a segfault. The same calamities can also occur in any constructor called by C<< <objrule:> >>. If the constructor invokes another regex in any way, it will most likely fail catastrophically. In particular, this means that Moose constructors will frequently crash and burn within a Regex::Grammars grammar (for example, if the Moose-based class declares an attribute type constraint such as 'Int', which Moose checks using a regex). Thanks for pointing out this non-obvious corner case. Damian


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