Source code line numbering

[Beatnik]

Category:

Miscellaneous

Description:

Just put use Filter::NumberLines; at the top of your source file (below the shebang). It will automagically number your lines starting from the line after the use statement. I'll probably have it on CPAN at some point. At the moment I stashed up at perlmonk.org. Examples are included and online.
Update: removed that second my on $line (thanks blakem).
I don't know if it's too obvious but it's not a regular line numbering script. It's a source filter :)))

package Filter::NumberLines;

use strict;
use vars qw($VERSION);
use Filter::Util::Call ;

$VERSION = '0.01';

my $line = 0;

sub import {
my ($type) = shift @_;
my ($ref) = [] ;
filter_add(bless $ref) ;
}

sub filter {
my ($self) = @_ ;
my ($status) ;
if (($status = filter_read()) > 0)
{ s/^\d+\:\t//; }
$status ;
}

open(F,"<$0") || die $!;
open(OUTFILE,">$0.bak") || die $!;
$line = 0;
my $no_go = 0;
my $past_use = 0;
$|++;
while(<F>)
{ $line++;
  if ($past_use && /^\d+\:\t/) { $no_go++;last; }
  if ($past_use)
  { $_ = sprintf ("%03d",$line).":\t".$_; }
  if (/use Filter\:\:NumberLines;/)
  { $past_use++; }
  print OUTFILE $_;
}
close(OUTFILE);
if (!$no_go)
{ unlink($0) || die $!;
  rename ("$0.bak",$0);
  close(F);
  exit;
} else { unlink("$0.bak") || die $!; }
1;
__END__
=pod

=head1 NAME

Filter::NumberLines - Source filter for Numbering lines.

=head1 SYNOPSIS

Just put use Filter::NumberLines; at the top of your source file (belo
+w the shebang).
It will automagically number your lines starting from the line after t
+he use statement.

  use Filter::NumberLines;

=head1 DESCRIPTION

Filter::NumberLines - Source filter for Numbering lines.

=head1 REQUIREMENTS

Filter::NumberLines requires Filter::Util::Call.

=head1 TODO

Make number of digits in line number configurable.

=head1 DISCLAIMER

This code is released under GPL (GNU Public License). More information
+ can be 
found on http://www.gnu.org/copyleft/gpl.html

=head1 VERSION

This is Filter::NumberLines 0.01.

=head1 AUTHOR

Hendrik Van Belleghem (beatnik -at- quickndirty -dot- org)

=head1 SEE ALSO

GNU & GPL - http://www.gnu.org/copyleft/gpl.html

Filter::Util::Call - http://search.cpan.org/search?dist=Filter

Paul Marquess' article
on Source Filters - http://www.samag.com/documents/s=1287/sam03030004/

=cut