Mail::Message::Head(3)User Contributed Perl DocumentatioMail::Message::Head(3)NAMEMail::Message::Head - the header of one message
INHERITANCEMail::Message::Head
is a Mail::Reporter
Mail::Message::Head is extended by
Mail::Box::IMAP4::Head
Mail::Message::Head::Complete
Mail::Message::Head::Delayed
Mail::Message::Head::Subset
SYNOPSIS
my $head = Mail::Message::Head->new;
$head->add('From: me@localhost');
$head->add(From => 'me@localhost');
$head->add(Mail::Message::Field->new(From => 'me'));
my $subject = $head->get('subject');
my @rec = $head->get('received');
$head->delete('From');
DESCRIPTION
"Mail::Message::Head" MIME headers are part of Mail::Message messages,
which are grouped in Mail::Box folders.
ATTENTION!!! most functionality about e-mail headers is described in
Mail::Message::Head::Complete, which is a matured header object. Other
kinds of headers will be translated to that type when time comes.
On this page, the general methods which are available on any header are
described. Read about differences in the sub-class specific pages.
OVERLOADED
overload: ""
(stringifaction) The header, when used as string, will format as if
Mail::Message::Head::Complete::string() was called, so return a
nicely folder full header. An exception is made for Carp, which
will get a simplified string to avoid unreadible messages from
"croak" and "confess".
example: using a header object as string
print $head; # implicit stringification by print
$head->print; # the same
print "$head"; # explicit stringication
overload: bool
When the header does not contain any lines (which is illegal,
according to the RFCs), false is returned. In all other cases, a
true value is produced.
METHODS
Constructors
Mail::Message::Head->build([PAIR|FIELD]-LIST)
A fast way to construct a header with many lines. The PAIRs are
"(name, content)" pairs of the header, but it is also possible to
pass Mail::Message::Field objects. A
Mail::Message::Head::Complete header is created by simply calling
Mail::Message::Head::Complete::build(), and then each field is
added. Double field names are permitted.
example:
my $subject = Mail::Message::Field->new(Subject => 'xyz');
my $head = Mail::Message::Head->build
( From => 'me@example.com'
, To => 'you@anywhere.aq'
, $subject
, Received => 'one'
, Received => 'two'
);
print ref $head;
# --> Mail::Message::Head::Complete
Mail::Message::Head->new(OPTIONS)
Create a new message header object. The object will store all the
fields of a header. When you get information from the header, it
will be returned to you as Mail::Message::Field objects, although
the fields may be stored differently internally.
If you try to instantiate a Mail::Message::Head, you will
automatically be upgraded to a Mail::Message::Head::Complete --a
full head.
-Option--Defined in --Default
field_type Mail::Message::Field::Fast
log Mail::Reporter 'WARNINGS'
message undef
modified <false>
trace Mail::Reporter 'WARNINGS'
field_type => CLASS
The type of objects that all the fields will have. This must be
an extension of Mail::Message::Field.
log => LEVEL
message => MESSAGE
The MESSAGE where this header belongs to. Usually, this is not
known at creation of the header, but sometimes it is. If not,
call the message() method later to set it.
modified => BOOLEAN
trace => LEVEL
The header
$obj->isDelayed
Headers may only be partially read, in which case they are called
delayed. This method returns true if some header information still
needs to be read. Returns false if all header data has been read.
Will never trigger completion.
$obj->isEmpty
Are there any fields defined in the current header? Be warned that
the header will not be loaded for this: delayed headers will return
true in any case.
$obj->isModified
Returns whether the header has been modified after being read.
example:
if($head->isModified) { ... }
$obj->knownNames
Like Mail::Message::Head::Complete::names(), but only returns the
known header fields, which may be less than "names" for header
types which are partial. "names()" will trigger completion, where
"knownNames()" does not.
$obj->message([MESSAGE])
Get (after setting) the message where this header belongs to. This
does not trigger completion.
$obj->modified([BOOLEAN])
Sets the modified flag to BOOLEAN. Without value, the current
setting is returned, but in that case you can better use
isModified(). Changing this flag will not trigger header
completion.
example:
$head->modified(1);
if($head->modified) { ... }
if($head->isModified) { ... }
$obj->orderedFields
Retuns the fields ordered the way they were read or added.
Access to the header
$obj->get(NAME [,INDEX])
Get the data which is related to the field with the NAME. The case
of the characters in NAME does not matter.
If there is only one data element defined for the NAME, or if there
is an INDEX specified as the second argument, only the specified
element will be returned. If the field NAME matches more than one
header the return value depends on the context. In LIST context,
all values will be returned in the order they are read. In SCALAR
context, only the last value will be returned.
example:
my $head = Mail::Message::Head->new;
$head->add('Received: abc');
$head->add('Received: xyz');
$head->add('Subject: greetings');
my @rec_list = $head->get('Received');
my $rec_scalar = $head->get('Received');
print ",@rec_list,$rec_scalar," # ,abc xyz, xyz,
print $head->get('Received', 0); # abc
my @sub_list = $head->get('Subject');
my $sub_scalar = $head->get('Subject');
print ",@sub_list,$sub_scalar," # ,greetings, greetings,
$obj->study(NAME [,INDEX])
Like get(), but puts more effort in understanding the contents of
the field. Mail::Message::Field::study() will be called for the
field with the specified FIELDNAME, which returns
Mail::Message::Field::Full objects. In scalar context only the last
field with that name is returned. When an INDEX is specified, that
element is returned.
About the body
$obj->guessBodySize
Try to estimate the size of the body of this message, but without
parsing the header or body. The result might be "undef" or a few
percent of the real size. It may even be very far of the real
value, that's why this is a guess.
$obj->isMultipart
Returns whether the body of the related message is a multipart
body. May trigger completion, when the "Content-Type" field is not
defined.
Internals
$obj->addNoRealize(FIELD)
Add a field, like Mail::Message::Head::Complete::add() does, but
avoid the loading of a possibly partial header. This method does
not test the validity of the argument, nor flag the header as
changed. This does not trigger completion.
$obj->addOrderedFields(FIELDS)
$obj->fileLocation
Returns the location of the header in the file, as a pair begin and
end. The begin is the first byte of the header. The end is the
first byte after the header.
$obj->load
Be sure that the header is loaded. This returns the loaded header
object.
$obj->moveLocation(DISTANCE)
Move the registration of the header in the file.
$obj->read(PARSER)
Read the header information of one message into this header
structure. This method is called by the folder object (some
Mail::Box sub-class), which passes the PARSER as an argument.
$obj->setNoRealize(FIELD)
Set a field, but avoid the loading of a possibly partial header as
set() does. This method does not test the validity of the
argument, nor flag the header as changed. This does not trigger
completion.
Error handling
$obj->AUTOLOAD
See "Error handling" in Mail::Reporter
$obj->addReport(OBJECT)
See "Error handling" in Mail::Reporter
$obj->defaultTrace([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])
Mail::Message::Head->defaultTrace([LEVEL]|[LOGLEVEL,
TRACELEVEL]|[LEVEL, CALLBACK])
See "Error handling" in Mail::Reporter
$obj->errors
See "Error handling" in Mail::Reporter
$obj->log([LEVEL [,STRINGS]])
Mail::Message::Head->log([LEVEL [,STRINGS]])
See "Error handling" in Mail::Reporter
$obj->logPriority(LEVEL)
Mail::Message::Head->logPriority(LEVEL)
See "Error handling" in Mail::Reporter
$obj->logSettings
See "Error handling" in Mail::Reporter
$obj->notImplemented
See "Error handling" in Mail::Reporter
$obj->report([LEVEL])
See "Error handling" in Mail::Reporter
$obj->reportAll([LEVEL])
See "Error handling" in Mail::Reporter
$obj->trace([LEVEL])
See "Error handling" in Mail::Reporter
$obj->warnings
See "Error handling" in Mail::Reporter
Cleanup
$obj->DESTROY
See "Cleanup" in Mail::Reporter
$obj->inGlobalDestruction
See "Cleanup" in Mail::Reporter
DETAILS
Ordered header fields
Many Perl implementations make a big mistake by disturbing the order of
header fields. For some fields (especially the resent groups, see
Mail::Message::Head::ResentGroup) the order shall be maintained.
MailBox will keep the order of the fields as they were found in the
source. When your add a new field, it will be added at the end. If
your replace a field with a new value, it will stay in the original
order.
Head class implementation
The header of a MIME message object contains a set of lines, which are
called fields (by default represented by Mail::Message::Field objects).
Dependent on the situation, the knowledge about the fields can be in
one of three situations, each represented by a sub-class of this
module:
· Mail::Message::Head::Complete
In this case, it is sure that all knowledge about the header is
available. When you get() information from the header and it is
not there, it will never be there.
· Mail::Message::Head::Subset
There is no certainty whether all header lines are known (probably
not). This may be caused as result of reading a fast index file,
as described in Mail::Box::MH::Index. The object is automatically
transformed into a Mail::Message::Head::Complete when all header
lines must be known.
· Mail::Message::Head::Partial
A partial header is like a subset header: probably the header is
incomplete. The means that you are not sure whether a get() for a
field fails because the field is not a part of the message or that
it fails because it is not yet known to the program. Where the
subset header knows where to get the other fields, the partial
header does not know it. It cannot hide its imperfection.
· Mail::Message::Head::Delayed
In this case, there is no single field known. Access to this
header will always trigger the loading of the full header.
Subsets of header fields
Message headers can be quite large, and therefore MailBox provides
simplified access to some subsets of information. You can grab these
sets of fields together, create and delete them as group.
On the moment, the following sets are defined:
· Mail::Message::Head::ResentGroup
A resent group is a set of fields which is used to log one step in
the transmission of the message from the original sender to the
destination.
Each step adds a set of headers to indicate when the message was
received and how it was forwarded (without modification). These
fields are best created using Mail::Message::bounce().
· Mail::Message::Head::ListGroup
Fields which are used to administer and log mailing list activity.
Mailing list software has to play trics with the original message
to be able to get the reply on that message back to the mailing
list. Usually a large number of lines are added.
· Mail::Message::Head::SpamGroup
A set of fields which contains header fields which are produced by
spam detection software. You may want to remove these fields when
you store a message for a longer period of time.
DIAGNOSTICS
Error: Package $package does not implement $method.
Fatal error: the specific package (or one of its superclasses) does
not implement this method where it should. This message means that
some other related classes do implement this method however the
class at hand does not. Probably you should investigate this and
probably inform the author of the package.
SEE ALSO
This module is part of Mail-Box distribution version 2.097, built on
January 26, 2011. Website: http://perl.overmeer.net/mailbox/
LICENSE
Copyrights 2001-2011 by Mark Overmeer. 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://www.perl.com/perl/misc/Artistic.html
perl v5.14.1 2011-01-26 Mail::Message::Head(3)
