Bug #68600 for Regexp-Grammars: objrule does not work with Moose nor AUTOLOAD

Hi Nathan, Thanks for the excellent bug-report, and especially for the numerous .t files, all of which have now been added to the distribution. Show quoted text
Both the problems you experienced stem from a single cause: the Perl regex engine is not re-entrant (at least, not prior to 5.14.0). The Moose problem you encountered is caused by the fact that some 'isa' type constraints are implemented by testing against regexes. In this case the 'isa' => 'INT' is the culprit. Changing it to something that isn't tested by regex (e.g. to: 'isa' => 'NUM') solves the problem. In the case of the various AUTOLOAD examples, the problem was that your AUTOLOAD() methods included a substitution: $var =~ s/.*://; Changing that line to the non-regex-based equivalent: my $last_colon_pos = rindex($var, ':'); substr $var, 0, $last_colon_pos+1, q{}; removes the problem for all the examples. The bottom line is that this is a perl issue, not a Regexp::Grammars issue. To solve it, you either have to avoid any class that uses regexes in its constructor, or you have to upgrade to 5.14.0. I have now added a new section to the documentation pointing out this inherent limitation of older Perl's: =head4 An important caveat regarding OO rules Prior to Perl 5.14.0, Perl's regex engine was not fully re-entrant. This means that in older versions of Perl, it is not possible to re-invoke the regex engine when already inside the regex engine. This means that you need to be careful that the C<new()> constructors that are called by your object-rules do not themselves use regexes in any way, unless you're running under Perl 5.14 or later (in which case you can ignore what follows). The two ways this is most likely to happen are: =over =item 1. If you're using a class built on Moose, where one or more of the C<has> uses a type constraint (such as C<'Int'>) that is implemented via regex matching. For example: has 'id' => (is => 'rw', isa => 'Int'); The workaround (for pre-5.14 Perls) is to replace the type constraint with one that doesn't use a regex. For example: has 'id' => (is => 'rw', isa => 'Num'); Alternatively, you could define your own type constraint that avoids regexes: use Moose::Util::TypeConstraints; subtype 'Non::Regex::Int', as 'Num', where { int($_) == $_ }; no Moose::Util::TypeConstraints; # and later... has 'id' => (is => 'rw', isa => 'Non::Regex::Int'); =item 2. If your class uses an C<AUTOLOAD()> method to implement its constructor and that method uses the typical: $AUTOLOAD =~ s/.*://; technique. The workaround here is to achieve the same effect without a regex. For example: my $last_colon_pos = rindex($AUTOLOAD, ':'); substr $AUTOLOAD, 0, $last_colon_pos+1, q{}; =back Note that this caveat against using nested regexes also applies to any code blocks executed inside a rule or token (whether or not those rules or tokens are object-oriented). Thanks again for bringing this to my attention, Nathan. Damian

On Wed, Jun 01, 2011 at 10:08:27PM -0400, damian@conway.org via RT wrote: Show quoted text
Thank you for the very clear new documentation, and swift turnaround. -kolibrie