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package Iterate; |
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|
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=for |
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Iterate - Smart, Simple, Recursive Iterators for Perl programming. |
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Copyright (C) 2002 Greg London |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the same terms as Perl 5 itself. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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Perl 5 License schemes for more details. |
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|
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contact the author via http://www.greglondon.com |
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=cut |
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|
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|
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require 5.005_62; |
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use strict; |
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use warnings; |
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|
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use Carp; |
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|
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require Exporter; |
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|
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our @ISA = qw(Exporter); |
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|
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# Items to export into callers namespace by default. Note: do not export |
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# names by default without a very good reason. Use EXPORT_OK instead. |
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# Do not simply export all your public functions/methods/constants. |
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|
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our @EXPORT = qw( |
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|
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IterArray |
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IterHash |
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IterFile |
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|
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); |
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our $VERSION = '0.01'; |
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|
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|
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|
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############################################################################## |
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sub IterArray(\@&) |
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############################################################################## |
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{ |
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my $arrayref = shift(@_); |
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my $callback = shift(@_); |
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|
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my $index; |
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my @return; |
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|
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my $wantarray = (defined(wantarray()) and wantarray()) ? 1 : 0; |
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#print "wantarray is $wantarray \n"; |
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|
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for(my $index=0; $index<scalar(@$arrayref); $index++) |
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{ |
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if($wantarray) |
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{ |
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push(@return, $callback->($arrayref->[$index], $index)); |
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} |
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else |
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{ |
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$callback->($arrayref->[$index], $index); |
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} |
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} |
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if($wantarray) |
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{ return (@return); } |
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else |
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{return;}} |
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|
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|
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|
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############################################################################## |
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sub IterHash(\%&) |
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############################################################################## |
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{ |
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my $hashref = shift(@_); |
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my $callback = shift(@_); |
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|
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my $arrayref = [keys(%$hashref)]; |
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my $index; |
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my @return; |
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|
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my $wantarray = (defined(wantarray()) and wantarray()) ? 1 : 0; |
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#print "wantarray is $wantarray \n"; |
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|
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for(my $index=0; $index<scalar(@$arrayref); $index++) |
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{ |
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if($wantarray) |
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{ |
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push(@return, $callback->($arrayref->[$index], $hashref->{$arrayref->[$index]}, $index)); |
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} |
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else |
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{ |
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$callback->($arrayref->[$index], $hashref->{$arrayref->[$index]}, $index); |
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} |
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} |
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|
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if($wantarray) |
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{ return (@return); } |
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else |
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{return;} |
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} |
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|
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|
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|
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############################################################################## |
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sub IterFile($&) |
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############################################################################## |
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{ |
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my $filename = shift(@_); |
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my $callback = shift(@_); |
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|
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my @return; |
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|
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my $wantarray = (defined(wantarray()) and wantarray()) ? 1 : 0; |
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#print "wantarray is $wantarray \n"; |
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|
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open ( my $filehandle, $filename ) or croak "Error: cannot open $filename"; |
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|
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my $linenumber=0; |
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while(<$filehandle>) |
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{ |
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$linenumber++; |
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if($wantarray) |
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{ |
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push(@return, $callback->($_, $linenumber)); |
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} |
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else |
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{ |
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$callback->($_, $linenumber); |
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} |
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} |
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close($filehandle) or croak "Error: cannot close $filename"; |
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if($wantarray) |
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{ return (@return); } |
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else |
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{return;} |
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} |
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|
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|
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1; |
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__END__ |
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|
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=head1 NAME |
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|
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Iterate - Smart, Simple, Recursive Iterators for Perl programming. |
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|
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=head1 SYNOPSIS |
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|
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use Iterate; |
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|
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# iterate an array, at index 3, change the value in the array to "three" |
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my @array = qw (alpha bravo charlie delta echo); |
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|
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IterArray @array, sub |
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{ |
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# $_[1] is the current numeric index |
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if($_[1] == 3) |
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{ |
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# modify the element in the original array |
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$_[0] = 'three'; # current element available via $_[0] |
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} |
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} |
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|
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|
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# iterate a hash, perform nested iteration on the same hash. |
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|
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my %hash = |
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( |
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blue => 'moon', |
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green => 'egg', |
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red => 'baron', |
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); |
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|
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IterHash (%hash, sub |
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{ |
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my $key1 = $_[0]; |
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my $val1 = $_[1]; |
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|
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print "checking key1 $key1, val1 $val1 for collisions \n"; |
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|
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IterHash (%hash, sub |
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{ |
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my $key2 = $_[0]; |
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my $val2 = $_[1]; |
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|
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print "\tchecking key2 $key2, val2 $val2 for collisions \n"; |
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print "\t $val2 is not $key1\n" |
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unless($key1 eq $key2); |
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return; |
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}); |
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}); |
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# iterate a file, read it line by line, and grep for a string. |
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IterFile "tfile.pl", sub |
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{ |
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# the line read from the file is stored in $_[0] |
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my $line = $_[0]; |
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|
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# the current line number corresponding to $_[0] is stored in $_[-1] |
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my $number = $_[-1]; |
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|
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if($line =~ /search/) |
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{ |
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print "found at line $number: $line"; |
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} |
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}; |
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|
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|
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=head1 DESCRIPTION |
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This module is intended to demonstrate a simple way to implement |
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iterators on perl variables with little code required of the |
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programmer using them. |
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|
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Some additional advantages over standard perl iterators: |
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|
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Array iterators give access to the current index within the array. |
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Hash iterators can be nested upon the same hash without conflicts. |
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File iterators allow simple file munging in a few lines of code. |
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|
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=head2 EXPORT |
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|
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IterArray |
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IterHash |
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IterFile |
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|
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=head1 AUTHOR |
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|
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Iterate - Smart, Simple, Recursive Iterators for Perl programming. |
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Copyright (C) 2002 Greg London |
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|
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This program is free software; you can redistribute it and/or modify |
| 241 |
it under the same terms as Perl 5 itself. |
| 242 |
|
| 243 |
This program is distributed in the hope that it will be useful, |
| 244 |
but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 245 |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 246 |
Perl 5 License schemes for more details. |
| 247 |
|
| 248 |
contact the author via http://www.greglondon.com |
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|
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|
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=head1 SEE ALSO |
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|
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perl(1). |
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|
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=cut |
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