NAME¶
Mail::Message::Head - the header of one message
INHERITANCE¶
Mail::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
- $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.
- $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¶
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.
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 2.105, built on May 07,
2012. Website:
http://perl.overmeer.net/mailbox/
LICENSE¶
Copyrights 2001-2012 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