NAME

Mail::Message::Field::Attribute - one attribute of a full field

SYNOPSIS

 my $field    = $msg->head->get('Content-Disposition') or return;
 my $full     = $field->study;   # full understanding in unicode
 my $filename = $full->attribute(filename)             or return;

 print ref $filename;     # this class name
 print $filename;         # the attributes content in utf-8
 print $filename->value;  # same
 print $filename->string; # print string as was found in the file
 $filename->print(\*OUT); # print as was found in the file

DESCRIPTION

Attributes within MIME fields can be quite complex, and therefore be slow and consumes a lot of memory. The Mail::Message::Field::Fast and Mail::Message::Field::Flex simplify them the attributes a lot, which may result in erroneous behavior in rare cases. With the increase of non-western languages on Internet, the need for the complex headers becomes more and more in demand.

A Mail::Message::Field::Attribute can be found in any structured Mail::Message::Field::Full header field.

METHODS

Initiation

addComponent STRING

A component is a parameter as defined by RFC2045, optionally using encoding or continuations as defined by RFC2231. Components of an attribute are found when a field is being parsed. The RFCs are very strict on valid characters, but we cannot be: you have to accept what is coming in if you can.

Examples:

 my $param = Mail::Message::Field::Attribute->new('Content-Type');
 $param->addComponent("filename*=iso10646'nl-BE'%Re\47u");

charset

Returns the character set which is used for this parameter. If any component is added which contains character set information, this is directly available. Be warned that a character-set is case insensitive.

language

Returns the language which is defined in the argument. If no language is defined undef is returned, which should be interpreted as "ANY"

name

Returns the name of this attribute.

new (NAME, [VALUE] | STRING), OPTIONS

(Class method) Create a new attribute NAME with the optional VALUE. If no VALUE is specified, the first argument of this method is inspected for an equals sign '='. If that character is present, the argument is taken as STRING, containing a preformatted attribute which is processed. Otherwise, the argument is taken as name without VALUE: set the value later with value().

Whether encoding takes place depends on the OPTIONS and the existence of non-ascii characters in the VALUE. The NAME can only contain ascii characters, hence is never encoded.

To speed things up, attributes are not derived from the Mail::Reporter base-class.

 OPTION               DEFAULT
 charset              'us-ascii'
 language             C<undef>
 use_continuations    1

charset => STRING

The VALUE is translated from utf-8 (Perl internal) to this character set, and the resulting string is encoded if required. us-ascii is the normal encoding for e-mail. Valid character sets can be found with Encode::encodings(':all').

language => STRING

RFC2231 adds the possiblity to specify a language with the field. When no language is specified, none is included in the encoding. Valid language names are defined by RFC2130. This module has only limited support for this feature.

use_continuations => BOOLEAN

Continuations are used to break-up long parameters into pieces which are no longer than 76 characters. Encodings are specified in RFC2231, but not supported by some Mail User Agents.

Examples:

 my $fn    = Mail::Message::Field::Attribute->new(filename => 'xyz');

 my $fattr = 'Mail::Message::Field::Attribute';  # abbrev
 my $fn    = $fattr->new
     ( filename => "Re\xC7u"
     , charset  => 'iso-8859-15'
     , language => 'nl-BE'
     );
 print $fn;   # print  filename*=iso-8859-15'nl-BE'Re%C7u

string

Returns the parameter as reference to an array of lines. When only one line is returned, it may be short enough to fit on the same line with other components of the header field.

value [STRING]

Returns the value of this parameter, optionally after setting it first.

Reading and Writing [internals]

decode

Translate all known continuations into a value. The produced value is returned and may be utf-8 encoded or a plain string.

encode

mergeComponent ATTRIBUTE

Merge the components from the specified attribute in this attribute. This is needed when components of the same attribute are created separately. Merging is required by the field parsing.

SEE ALSO

A good start to read is Mail::Box-Overview. More documentation and a mailinglist are available from the project's website at http://perl.overmeer.net/mailbox/.

AUTHOR

Written by Mark Overmeer (mark@overmeer.net) with the help of many. See the ChangeLog for details.

VERSION

This code is beta, version 2.037.

Copyright (c) 2001-2003 by the authors. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.