Provided by: libmail-message-perl_3.015-1_all 
NAME
Mail::Message::Body::Encode - organize general message encodings
SYNOPSIS
my Mail::Message $msg = ...;
my $decoded = $msg->decoded;
my $encoded = $msg->encode(mime_type => 'image/gif',
transfer_encoding => 'base64');
my $body = $msg->body;
my $decoded = $body->decoded;
my $encoded = $body->encode(transfer_encoding => '7bit');
DESCRIPTION
Manages the message's body encodings and decodings on request of the main program. This package adds
functionality to the Mail::Message::Body class when the decoded() or encode() method is called.
Four types of encodings are handled (in the right order)
• eol encoding
Various operating systems have different ideas about how to encode the line termination. UNIX uses a
LF character, MacOS uses a CR, and Windows uses a CR/LF combination. Messages which are transported
over Internet will always use the CRLF separator.
• transfer encoding
Messages transmitted over Internet have to be plain ASCII. Complicated characters and binary files
(like images and archives) must be encoded during transmission to an ASCII representation.
The implementation of the required encoders and decoders is found in the Mail::Message::TransferEnc
set of packages. The related manual page lists the transfer encodings which are supported.
• mime-type translation
NOT IMPLEMENTED YET
• charset conversion
METHODS
Constructing a body
$obj->charsetDetect(%options)
[3.013] This is tricky. It is hard to detect whether the body originates from the program, or from
an external source. And what about a database database? are those octets or strings? Please read
"Autodetection of character-set" in Mail::Message::Body.
-Option --Default
external <false>
external => BOOLEAN
Do only consider externally valid character-sets, implicitly: "PERL" is not an acceptable answer.
Mail::Message::Body->charsetDetectAlgorithm( [CODE|undef|METHOD] )
[3.013] When a body object does not specify its character-set, but that detail is required, then it
gets autodetected. The default algorithm is implemented in charsetDetect(). You may change this
default algorithm, or pass option "charset_detect" for each call to encode().
When you call this method with an explicit "undef", you reset the default. (Without parameter) the
current algorithm (CODE or method name) is returned.
$obj->check()
Check the content of the body not to include illegal characters. Which characters are considered
illegal depends on the encoding of this body.
A body is returned which is checked. This may be the body where this method is called upon, but also
a new object, when serious changes had to be made. If the check could not be made, because the
decoder is not defined, then "undef" is returned.
$obj->encode(%options)
Encode (translate) a Mail::Message::Body into a different format. See the DESCRIPTION above.
Options which are not specified will not trigger conversions.
-Option --Default
charset PERL
charset_detect <built-in>
mime_type undef
result_type <same as source>
transfer_encoding undef
charset => CHARSET|'PERL'
Only applies when the mime_type is textual.
If the CHARSET is explicitly specified (for instance "iso-8859-10", then the data is being
interpreted as raw bytes (blob), not as text. However, in case of "PERL", it is considered to be
an internal representation of characters (either latin1 or Perl's utf8 --not the same as utf-8--,
you should not want to know).
This setting overrules the charset attribute in the mime_type FIELD.
charset_detect => CODE
[3.013] When the body does not contain an explicit charset specification, then the RFC says it is
"us-ascii". In reality, this is not true: it is just an unknown character set. This often happens
when text files are included as attachment, for instance a footer attachment.
When you want to be smarter than the default charset detector, you can provide your own function
for this parameter. The function will get the transfer-decoded version of this body. You can
change the default globally via charsetDetectAlgorithm().
mime_type => STRING|FIELD
Convert into the specified mime type, which can be specified as STRING or FIELD. The FIELD is a
Mail::Message::Field-object, representing a "Content-Type" mime header. The STRING must be valid
content for such header, and will be converted into a FIELD object.
The FIELD may contain attributes. Usually, it has a "charset" attribute, which explains the
CHARSET of the content after content transfer decoding. The "charset" option will update/add this
attribute. Otherwise (hopefully in rare cases) the CHARSET will be auto-detected when the body
gets decoded.
result_type => CLASS
The type of body to be created when the body is changed to fulfill the request on re-coding. Also
the intermediate stages in the translation process (if needed) will use this type. CLASS must
extend Mail::Message::Body.
transfer_encoding => STRING|FIELD
$obj->encoded(%options)
Encode the body to a format what is acceptable to transmit or write to a folder file. This returns
the body where this method was called upon when everything was already prepared, or a new encoded
body otherwise. In either case, the body is checked.
-Option --Default
charset_detect <the default>
charset_detect => CODE
See charsetDetectAlgorithm().
$obj->unify($body)
Unify the type of the given $body objects with the type of the called body. "undef" is returned when
unification is impossible. If the bodies have the same settings, the $body object is returned
unchanged.
Examples:
my $bodytype = Mail::Message::Body::Lines;
my $html = $bodytype->new(mime_type=>'text/html', data => []);
my $plain = $bodytype->new(mime_type=>'text/plain', ...);
my $unified = $html->unify($plain);
# $unified is the data of plain translated to html (if possible).
About the payload
$obj->dispositionFilename( [$directory] )
Various fields are searched for "filename" and "name" attributes. Without $directory, the name found
will be returned unmodified.
When a $directory is given, a filename is composed. For security reasons, only the basename of the
found name gets used and many potentially dangerous characters removed. If no name was found, or
when the found name is already in use, then an unique name is generated.
Don't forget to read RFC6266 section 4.3 for the security aspects in your email application.
$obj->isBinary()
Returns true when the un-encoded message is binary data. This information is retrieved from
knowledge provided by MIME::Types.
$obj->isText()
Returns true when the un-encoded message contains printable text.
Internals
$obj->addTransferEncHandler( $name, <$class|$object> )
Mail::Message::Body->addTransferEncHandler( $name, <$class|$object> )
Relate the NAMEd transfer encoding to an OBJECTs or object of the specified $class. In the latter
case, an object of that $class will be created on the moment that one is needed to do encoding or
decoding.
The $class or $object must extend Mail::Message::TransferEnc. It will replace existing class and
object for this $name.
Why aren't you contributing this class to MailBox?
$obj->getTransferEncHandler($type)
Get the transfer encoder/decoder which is able to handle $type, or return undef if there is no such
handler.
DIAGNOSTICS
Warning: Charset $name is not known
The encoding or decoding of a message body encounters a character set which is not understood by
Perl's Encode module.
Warning: No decoder defined for transfer encoding $name.
The data (message body) is encoded in a way which is not currently understood, therefore no decoding
(or recoding) can take place.
Warning: No encoder defined for transfer encoding $name.
The data (message body) has been decoded, but the required encoding is unknown. The decoded data is
returned.
SEE ALSO
This module is part of Mail-Message distribution version 3.015, built on December 11, 2023. Website:
http://perl.overmeer.net/CPAN/
LICENSE
Copyrights 2001-2023 by [Mark Overmeer <markov@cpan.org>]. For other contributors see ChangeLog.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl
itself. See http://dev.perl.org/licenses/
perl v5.36.0 2023-12-11 Mail::Message::Body::Encode(3pm)