in reply to Re: Re: Code critique XS function for extracting a blessed regex's pattern.
in thread Code critique XS function for extracting a blessed regex's pattern.

My question is this: given an arbitrary blessed scalar ref, how does one efficiently determine if the object is in fact a regex?

Once you bless a Regexp into another class it isn't a Regexp anymore... try:

<update>As demerphq kindly pointed out I lied :-) Can you spot the silly mistake in the "demonstration" below :-)</update>

my $bqr=bless qr/^blessed$/,"Foo";
print "no match for $bqr\n" unless "normal" =~ m/$bqr/;

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:-)

I guess you could subclass it (although this is something I've never tried) - in which case

UNIVERSAL::isa($qr, 'Regexp')

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would be the right solution.

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Re: Re: Re: Re: Code critique XS function for extracting a blessed regex's pattern.
by demerphq (Chancellor) on Feb 06, 2003 at 01:31 UTC
    Once you bless a Regexp into another class it isn't a Regexp anymore...

    Nope. The magic doesn't go away. As you can see. 

    sub t {
    printf "%10s %s /%s/\n",
         $_[0],
         ($_[0]=~/$_[1]/ ? "=~" : "!="),
         $_[1];
};

$bqr=bless qr/^blessed$/,"Foo";
$qr=qr/^normal$/;

foreach $rex ($bqr,$qr) {
    t($_,$rex)
        foreach qw(normal blessed);
}

__END__
    normal != /Foo=SCALAR(0x1abf1d8)/
   blessed =~ /Foo=SCALAR(0x1abf1d8)/
    normal =~ /(?-xism:^normal$)/
   blessed != /(?-xism:^normal$)/

    [download]
    In fact i think its considered a feature. The possibilities are kinda interesting. :-)

    --- demerphq
    my friends call me, usually because I'm late....

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[d/l]

      D'oh - learn something new every day! Thanks for putting this poor fool straight :-)

      (Moral - don't type code examples at 1am. Bad adrian)

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