NAME

       Convert::YText - Quotes strings suitably for rfc2822 local part

VERSION

       Version 0.1

SYNOPSIS

       use Convert::YText qw(encode_ytext decode_ytext);

       $encoded=encode_ytext($string); $decoded=decode_ytext($encoded);

       ($decoded eq $string) || die "this should never happen!";

DESCRIPTION

       Convert::YText converts strings to and from "YText", a format inspired by xtext defined in
       RFC1894, the MIME base64 and quoted-printable types (RFC 1394).  The main goal is encode a
       UTF8 string into something safe for use as the local part in an internet email address
       (RFC2822).

       By default spaces are replaced with "+", "/" with "~", the characters "A-Za-z0-9_.-"
       encode as themselves, and everything else is written "=USTR=" where USTR is the base64
       (using "A-Za-z0-9_." as digits) encoding of the unicode character code.  The encoding is
       configurable (see below).

PROCEDURAL INTERFACE

       The module can can export "encode_ytext" which converts arbitrary unicode string into a
       "safe" form, and "decode_ytext" which recovers the original text.  "validate_ytext" is a
       heuristic which returns 0 for bad input.

OBJECT ORIENTED INTERFACE.

       For more control, you will need to use the OO interface.

   new
       Create a new encoding object.

       Arguments

       Arguments are by name (i.e. a hash).

       DIGIT_STRING ("A-Za-z0-9_.") Must be 64 characters long
       ESCAPE_CHAR ('=') Must not be in digit string.
       SPACE_CHAR ('+') Non digit to replace space. Can be the empty string.
       SLASH_CHAR ( '~') Non digit to replace slash. Can be the empty string.
       EXTRA_CHARS ('._\-') Other characters to leave unencoded.

   encode
       Arguments

       a string to encode.

       Returns

       encoded string

   decode
       Arguments

       a string to decode.

       Returns

       encoded string

   valid
       Simple necessary but not sufficient test for validity.

DISCUSSION

       According to RFC 2822, the following non-alphanumerics are OK for the local part of an
       address: "!#$%&'*+-/=?^_`{|}~". On the other hand, it seems common in practice to block
       addresses having "%!/|`#&?" in the local part.  The idea is to restrict ourselves to basic
       ASCII alphanumerics, plus a small set of printable ASCII, namely "=_+-~.".

       The characters '+' and '-' are pretty widely used to attach suffixes (although usually
       only one works on a given mail host). It seems ok to use '+-', since the first marks the
       beginning of a suffix, and then is a regular character. The character '.' also seems
       mostly permissable.

AUTHOR

       David Bremner, <ddb@cpan.org<gt>

COPYRIGHT

       Copyright (C) 2011 David Bremner.  All Rights Reserved.

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

SEE ALSO

       MIME::Base64, MIME::Decoder::Base64, MIME::Decoder::QuotedPrint.