in reply to Re: regex question - dynamically address captures
in thread regex question - dynamically address captures

Nice, but you should replace 

next if $line !~ /$patterns{$key}->{regex}/;
my @captures = map {substr $line, $-[$_], $+[$_] - $-[$_] + 1} 1..$#-;

[download]

with the much simpler 

my @captures = $line =~ /$patterns{$key}->{regex}/
  or next;

[download]

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Re^3: regex question - dynamically address captures
by GrandFather (Saint) on Feb 21, 2006 at 23:22 UTC

    Argh. I had the equivelent of that first off, but I'd used 1 for the section and para numbers so @captures contained a single element with the value 1 and I convinced myself that it was the match count.

    Candidate for OT: most egregious programming error, ever maybe? :)

    DWIM is Perl's answer to Gödel
[reply]
      Well, it will place 1 (success flag) in @captures when there are no captures in the regexp, but that shouldn't matter since there shouldn't be any id_fields when there are no captures.
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Re^3: regex question - dynamically address captures
by nmerriweather (Friar) on Feb 21, 2006 at 23:23 UTC
    a_ AWESOME. thank you both.

    b_ the +1 on the substr should be cut.
[reply]
      On further investigation, it appears GrandFather's solution, as corrected by nmerriweather, is correct. ikegami's solution passes a 1 into @captures in the case of a successful match with no captures requested. This doesn't DWIM, and it proved to be a deal-breaker in my real-world task. 

      my $line = q{Convention_9841_12345678901234.txt};
my @captures;

print "\nIncorrect\n\n";

print_captures( incorrect( qr/Convention_(\d{4})_(\d{14})\.txt$/, $lin
+e ) );

print_captures( incorrect( qr/Convention_(\d{4})_\d{14}\.txt$/, $line 
+) );

print_captures( incorrect( qr/Convention_\d{4}_\d{14}\.txt$/, $line ) 
+);

print_captures( incorrect( qr/Convention_((\d{4})_(\d{14}))\.txt$/, $l
+ine ) );

print_captures( incorrect( qr/^(.*Convention_(\d{4})_(\d{14})\.txt)$/,
+ $line ) );
print "\nCorrect\n\n";
print_captures( get_captures( qr/Convention_(\d{4})_(\d{14})\.txt$/, $
+line ) );

print_captures( get_captures( qr/Convention_(\d{4})_\d{14}\.txt$/, $li
+ne ) );

print_captures( get_captures( qr/Convention_\d{4}_\d{14}\.txt$/, $line
+ ) );

print_captures( get_captures( qr/Convention_((\d{4})_(\d{14}))\.txt$/,
+ $line ) );

print_captures( get_captures( qr/^(.*Convention_(\d{4})_(\d{14})\.txt)
+$/, $line ) );

sub incorrect {
    my ($pattern, $line) = @_;
    my @captures;
    (@captures) = $line =~ m/$pattern/ or return;
    return @captures;
}

sub get_captures {
    my ($pattern, $line) = @_;
    $line =~ m/$pattern/ or return;
    return map {substr $line, $-[$_], $+[$_] - $-[$_]} (1 .. $#-);
}

sub print_captures {
    my @captures = @_;
    @captures ? print "captures:  @captures\n" : print "no captures\n"
+;
}

      [download]

      Jim Keenan
[reply]
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        More readable: 
        sub get_captures {
    my ($pattern, $line) = @_;
    my @captures = $line =~ m/$pattern/;
    shift(@captures) if !$#+;
    return @captures;
}

        [download]
        or 
        sub get_captures {
    my ($pattern, $line) = @_;
    my @captures = $line =~ m/($pattern)/;
    shift(@captures);
    return @captures;
}

        [download]
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Re^3: regex question - dynamically address captures
by jkeenan1 (Deacon) on Jul 09, 2006 at 00:54 UTC
    Your response and Grandfather's have solved an important problem for me on my day job. Thank you, fellow monks!

    Jim Keenan
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