Acme::Metification - Give Perl the power of Metaprogramming!

Acme-Metification documentation Contained in the Acme-Metification distribution.

Index

Code Index:

NAME

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Acme::Metification - Give Perl the power of Metaprogramming!

SYNOPSIS

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  use Acme::Metification;
  # This is line 0

  sub faculty {
     my $no = shift;
     my $fac = 1;
     $fac *= ($no--);
     return $fac if $no == 0;
     recursemeta depth => 100, 5, 7
     # ^^ insert lines 5 to 7 up to 100 times
     return $fac;
  }

  print faculty(4); # prints 24 after quite some time

NOTE

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Do not, I repeat, do not use in production code. But then again, the features are useless, so you wouldn't anyway.

DESCRIPTION

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This module gives you some meta-programming abilites within Perl. It uses source filters to do evil things with your source.

The module allows the use of two new functions. They must appear on separate lines in your code:

meta

Syntax:

  meta [line_no1], [line_no2]

meta replaces itself with the code lines ranging from [line_no1] to [line_no2]. The first line after "use Acme::Metification;" is considered line 0.

Of course, those lines may contain meta or recursemeta directives, so beware of deep recursion.

recursemeta

Similar to meta with some exceptions. Syntax:

  recursemeta depth => [depth], [line_no1], [line_no2]

[depth] is the maximum depth to recurse into in case recursemeta directives are inserted. However, meta directives will be recursed into deeply.

EXAMPLES

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Execute examples from POD docs
  use Acme::Metification;

  # Execute code from pod docs:

  meta 9, 11

  =pod

  =head1 Example

    foreach (0..5) {
      print "Acme::Metification rocks!\n";
    }

  =cut
Transform slow recursion into blazingly fast code!
  use Acme::Metification;

  sub faculty {
     my $no = shift;
     my $fac = 1;
     $fac *= ($no--);
     return $fac if $no == 0;
     recursemeta depth => 100, 4, 6
     return $fac;
  }

  print faculty(4);

AUTHOR

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Steffen Mueller, <smueller@cpan.org<gt>

COPYRIGHT AND LICENSE

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Copyright (c) 2002-2006 Steffen Mueller. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

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Filter::Simple by Damian Conway

Acme-Metification documentation Contained in the Acme-Metification distribution. 
package Acme::Metification;

use 5.006;
use strict;
use warnings;

use vars qw /$VERSION/;
$VERSION = '1.01';

use Filter::Simple;

# Call the filter routine supplied by Filter::Simple.
# It is time to read the Filter::Simple man page now if you
# haven't done so yet.

# Then pray :) This is ugly.

FILTER_ONLY
   all  => \&_filter_all,     # Used to get the source code lines
   code => \&_filter_recurse, # Used to filter recursive replacements
                             # of limited depth
   code => \&_filter_meta;#,    # Used to filter replacements
#   all => sub {my $co=0;my $c=$_;$c=~s/\n/$co++."\n"/sge;print $c;$_};

my @src_lines;

sub _filter_all {
   if (@src_lines) {
      die "Filter invoked multiple times. Not supported in this version!";
   }
   @src_lines = split /\n/;

   $_;
};


sub _filter_meta {
   while (
          s{^\s*meta\s*(.*)}{
                                                              _replace_meta($1)
                                                        }mge
         ) {}
}

sub _filter_recurse {

    while (
       s{^\s*recursemeta\s*depth\s*\=\>\s*(\d+)\s*,\s*(.+)}!
                    my $depth = $1-1;
                    my $rep = _replace_meta($2);
                    if ($depth > 0) {
                          $rep =~ s{^\s*recursemeta\s*depth\s*\=\>\s*(\d+)\s*,\s*(.+)}|
                                "recursemeta depth => " . ($depth) . ", $2"
                          |mge;
                    } else { $rep =~ s{^\s*recursemeta\s*depth\s*\=\>\s*(\d+)\s*,\s*(.+)}||mg }
                  $rep;
              !mge
    ) {}
}

sub _replace_meta {
   my $match = shift;
   $match =~ /(\d+)\s*,\s*(\d+)/ or $match =~ /(\d+)/;

   my ($start, $end) = ($1, $2);

   return '' if not defined $start;

   $start = int $start;
   $start = @src_lines + $start if $start < 0;
   $start = $#src_lines if $start > $#src_lines;

   return $src_lines[$start] if not defined $end;

   $end   = int $end;
   $end   = @src_lines + $end if $end   < 0;
   $end   = $#src_lines if $end > $#src_lines;

   ($start, $end) = ($end, $start) if $start > $end;

   return join "\n", (@src_lines[($start .. $end)]);
}

1;

__END__