NAME

PerlIO::via::Rotate - PerlIO layer for encoding using rotational deviation

SYNOPSIS

 use PerlIO::via::Rotate;           # assume rot13 only
 use PerlIO::via::Rotate 13,14,15;  # list rotations (rotxx) to be used
 use PerlIO::via::Rotate ':all';    # allow for all possible rotations 0..26

 open( my $in,'<:via(rot13)','file.rotated' )
  or die "Can't open file.rotated for reading: $!\n";
 
 open( my $out,'>:via(rot14)','file.rotated' )
  or die "Can't open file.rotated for writing: $!\n";

DESCRIPTION

This module implements a PerlIO layer that works on files encoded using rotational deviation. This is a simple manner of encoding in which pure alphabetical letters (a-z and A-Z) are moved up a number of places in the alphabet.

The default rotation is "13". Commonly this type of encoding is referred to as "rot13" encoding. However, any rotation between 0 and 26 inclusive are allowed (albeit that rotation 0 and 26 don't change anything). You can specify the rotations you would like to use as a list in the -use- statement.

The special keyword ":all" can be specified in the -use- statement to indicate that all rotations between 0 and 26 inclusive should be allowed.

REQUIRED MODULES

 (none)

CAVEATS

This module is special insofar it serves as a front-end for 27 modules that are named "PerlIO::via::rot0" through "PerlIO::via::rot26" that are eval'd as appropriate when the module is -use-d. The reason for this approach is that it is currently impossible to pass parameters to a PerlIO layer when opening a file. The name of the module is the implicit parameter being passed to the PerlIO::via::Rotate module.

ACKNOWLEDGEMENTS

Inspired by Crypt::Rot13.pm by Julian Fondren.

CPAN RT