Mail::Message::Field - one line of a message header
Mail::Message::Field is a Mail::Reporter Mail::Message::Field is extended by Mail::Message::Field::Fast Mail::Message::Field::Flex Mail::Message::Field::Full
my $field = Mail::Message::Field->new(From => 'firstname.lastname@example.org'); print $field->name; print $field->body; print $field->comment; print $field->content; # body & comment $field->print(\*OUT); print $field->string; print "$field\n"; print $field->attribute('charset') || 'us-ascii';
This implementation follows the guidelines of rfc2822 as close as possible, and may there produce a different output than implementations based on the obsolete rfc822. However, the old output will still be accepted.
These objects each store one header line, and facilitates access routines to the information hidden in it. Also, you may want to have a look at the added methods of a message:
my @from = $message->from; my $sender = $message->sender; my $subject = $message->subject; my $msgid = $message->messageId; my @to = $message->to; my @cc = $message->cc; my @bcc = $message->bcc; my @dest = $message->destinations; my $other = $message->get('Reply-To');
(stringification) produces the unfolded body of the field, which may be what you expect. This is what makes what the field object seems to be a simple string. The string is produced by unfoldedBody().
print $msg->get('subject'); # via overloading print $msg->get('subject')->unfoldedBody; # same my $subject = $msg->get('subject') || 'your mail'; print "Re: $subject\n";
(numification) When the field is numeric, the value will be returned. The result is produced by toInt(). If the value is not correct, a
0 is produced, to simplify calculations.
(numeric comparison) Compare the integer field contents with something else.
if($msg->get('Content-Length') > 10000) ... if($msg->size > 10000) ... ; # same, but better
Always true, to make it possible to say
(string comparison) Compare the unfolded body of a field with an other field or a string, using the buildin
Create a copy of this field object.
-Option--Defined in --Default log Mail::Reporter 'WARNINGS' trace Mail::Reporter 'WARNINGS'
Some fields are described in the RFCs as being structured: having a well described syntax. These fields have common ideas about comments and the like, what they do not share with unstructured fields, like the
my $field = Mail::Message::Field->new(From => 'me'); if($field->isStructured) Mail::Message::Field->isStructured('From');
Returns the total length of the field in characters, which includes the field's name, body and folding characters.
Returns the number of lines needed to display this header-line.
Print the whole header-line to the specified file-handle. One line may result in more than one printed line, because of the folding of long lines. The FILEHANDLE defaults to the selected handle.
Returns the number of bytes needed to display this header-line, Same as length().
Returns the field as string. By default, this returns the same as folded(). However, the optional WRAP will cause to re-fold to take place (without changing the folding stored inside the field).
Returns whether this field can be disclosed to other people, for instance when sending the message to an other party. Returns a
false condition. See also Mail::Message::Head::Complete::printUndisclosed().
Returns the name of this field in original casing. See name() as well.
Returns the name of this field, with all characters lower-cased for ease of comparison. See Name() as well.
(Instance method class method) As instance method, the current field's name is correctly formatted and returned. When a STRING is used, that one is formatted.
print Mail::Message::Field->Name('content-type') # --> Content-Type my $field = $head->get('date'); print $field->Name; # --> Date
Returns the body of the field. When this field is structured, it will be stripped from everything what is behind the first semi-color (
;). In any case, the string is unfolded. Whether the field is structured is defined by isStructured().
Returns the folded version of the whole header. When the header is shorter than the wrap length, a list of one line is returned. Otherwise more lines will be returned, all but the first starting with at least one blank. See also foldedBody() to get the same information without the field's name.
In scalar context, the lines are delived into one string, which is a little faster because that's the way they are stored internally...
my @lines = $field->folded; print $field->folded; print scalar $field->folded; # faster
Returns the body as a set of lines. In scalar context, this will be one line containing newlines. Be warned about the newlines when you do pattern-matching on the result of thie method.
The optional BODY argument changes the field's body. The folding of the argument must be correct.
Remove the comments and folding white spaces from the STRING. Without string and only as instance method, the unfoldedBody() is being stripped and returned.
WARNING: This operation is only allowed for structured header fields (which are defined by the various RFCs as being so. You don't want parts within braces which are in the Subject header line to be removed, to give an example.
Returns the body as one single line, where all folding information (if available) is removed. This line will also NOT end on a new-line.
The optional BODY argument changes the field's body. The right folding is performed before assignment. The WRAP may be specified to enforce a folding size.
my $body = $field->unfoldedBody; print "$field"; # via overloading
Returns a list of Mail::Address objects, which represent the e-mail addresses found in this header line.
my @addr = $message->head->get('to')->addresses; my @addr = $message->to;
Get the value of an attribute, optionally after setting it to a new value. Attributes are part of some header lines, and hide themselves in the comment field. If the attribute does not exist, then
undef is returned. The attribute is still encoded.
my $field = Mail::Message::Field->new( 'Content-Type: text/plain; charset="us-ascii"'); print $field->attribute('charset'); # --> us-ascii print $field->attribute('bitmap') || 'no' # --> no $field->atrribute(filename => '/tmp/xyz'); $field->print; # --> Content-Type: text/plain; charset="us-ascii"; # filename="/tmp/xyz" # Automatically folded, and no doubles created.
Returns a list of key-value pairs, where the values are not yet decoded.
my %attributes = $head->get('Content-Disposition')->attributes;
Returns the unfolded comment (part after a semi-colon) in a structureed header-line. optionally after setting it to a new STRING first. When
undef is specified as STRING, the comment is removed. Whether the field is structured is defined by isStructured().
The comment part of a header field often contains
attributes. Often it is preferred to use attribute() on them.
Study the header field in detail: turn on the full parsing and detailed understanding of the content of the fields. Mail::Message::Field::Fast and Mail::Message::Field::Fast objects will be transformed into any Mail::Message::Field::Full object.
my $subject = $msg->head->get('subject')->study; my $subject = $msg->head->study('subject'); # same my $subject = $msg->study('subject'); # same
Convert a timestamp into an rfc2822 compliant date format. This differs from the default output of
localtime in scalar context. Without argument, the
localtime is used to get the current time. TIME can be specified as one numeric (like the result of
time()) and as list (like produced by c<localtime()> in list context).
Be sure to have your timezone set right, especially when this script runs automatically.
my $now = time; Mail::Message::Field->toDate($now); Mail::Message::Field->toDate(time); Mail::Message::Field->toDate(localtime); Mail::Message::Field->toDate; # same # returns someting like: # Wed, 28 Aug 2002 10:40:25 +0200
Returns the value which is related to this field as integer. A check is performed whether this is right.
Convert a STRING which represents and RFC compliant time string into a timestamp like is produced by the
Accepts a whole field LINE, or a pair with the field's NAME and BODY. In the latter case, the BODY data may be specified as array of OBJECTS which are stringified. Returned is a nicely formatted pair of two strings: the field's name and a folded body.
Any field from any header for any message will have this default wrapping. This is maintained in one global variable. Without a specified LENGTH, the current value is returned. The default is 78.
Make the header field with NAME fold into multiple lines. Wrapping is performed by inserting newlines before a blanks in the BODY, such that no line exceeds the MAXCHARS and each line is as long as possible.
The RFC requests for folding on nice spots, but this request is mainly ignored because it would make folding too slow.
Force the wrapping of this field to the specified LENGTH characters. The wrapping is performed with fold() and the results stored within the field object.
example: refolding the field
This method implements the translation of user supplied objects into ascii fields. The process is explained in "Specifying field data".
The reverse action of fold(): all lines which form the body of a field are joined into one by removing all line terminators (even the last). Possible leading blanks on the first line are removed as well.
Fields are stored in the header of a message, which are represented by Mail::Message::Head objects. A field is a combination of a name, body, and attributes. Especially the term "body" is cause for confusion: sometimes the attributes are considered to be part of the body.
The name of the field is followed by a colon ("
:", not preceded by blanks, but followed by one blank). Each attribute is preceded by a separate semi-colon ("
;"). Names of fields are case-insensitive and cannot contain blanks.
Fields which are long can be folded to span more than one line. The real limit for lines in messages is only at 998 characters, however such long lines are not easy to read without support of an application. Therefore rfc2822 (which defines the message syntax) specifies explicitly that field lines can be re-formatted into multiple sorter lines without change of meaning, by adding new-line characters to any field before any blank or tab.
Usually, the lines are reformatted to create lines which are 78 characters maximum. Some applications try harder to fold on nice spots, like before attributes. Especially the
Received field is often manually folded into some nice layout. In most cases however, it is preferred to produce lines which are as long as possible but max 78.
BE WARNED that all fields can be subjected to folding, and that you usually want the unfolded value.
The rfc2822 describes a large number of header fields explicitly. These fields have a defined meaning. For some of the fields, like the
Subject field, the meaning is straight forward the contents itself. These fields are the Unstructured Fields.
Other fields have a well defined internal syntax because their content is needed by e-mail applications. For instance, the
To field contains addresses which must be understood by all applications in the same way. These are the Structured Fields, see isStructured().
Stuctured fields can contain comments, which are pieces of text enclosed in parenthesis. These comments can be placed close to anywhere in the line and must be ignored be the application. Not all applications are capable of handling comments correctly in all circumstances.
As many programs as there are handling e-mail, as many variations on accessing the header information are requested. Be careful which way you access the data: read the variations described here and decide which solution suites your needs best.
get() interface is copied from other Perl modules which can handle e-mail messages. Many applications which simply replace Mail::Internet objects by Mail::Message objects will work without modification.
There is more than one get method. The exact results depend on which get you use. When Mail::Message::get() is called, you will get the unfolded, stripped from comments, stripped from attributes contents of the field as string. Character-set encodings will still be in the string. If the same fieldname appears more than once in the header, only the last value is returned.
When Mail::Message::Head::get() is called in scalar context, the last field with the specified name is returned as field object. This object strinigfies into the unfolded contents of the field, including attributes and comments. In list context, all appearances of the field in the header are returned as objects.
BE WARNED that some lines seem unique, but are not according to the official rfc. For instance,
To fields can appear more than once. If your program calls
get('to') in scalar context, some information is lost.
As the name
study already implies, this way of accessing the fields is much more thorough but also slower. The
study of a field is like a
get, but provides easy access to the content of the field and handles character-set decoding correctly.
Some fields belong together in a group of fields. For instance, a set of lines is used to define one step in the mail transport process. Each step adds a
Received line, and optionally some
Resent-* lines and
Return-Path. These groups of lines shall stay together and in order when the message header is processed.
Mail::Message::Head::ResentGroup object simplifies the access to these related fields. These resent groups can be deleted as a whole, or correctly constructed.
There are many ways to get the fields info as object, and there are also many ways to process this data within the field.
Returns the text of the body exactly as will be printed to file when print() is called, so name, main body, and attributes.
Returns the text of the body, like string(), but without the name of the field.
Returns the text of the body, like foldedBody(), but then with all new-lines removed. This is the normal way to get the content of unstructured fields. Character-set encodings will still be in place. Fields are stringified into their unfolded representation.
Returns the text of structured fields, where new-lines and comments are removed from the string. This is a good start for parsing the field, for instance to find e-mail addresses in them.
Studied fields can produce the unfolded text decoded into utf8 strings. This is an expensive process, but the only correct way to get the field's data. More useful for people who are not living in ASCII space.
Studied fields have powerful methods to provide ways to access and produce the contents of (structured) fields exactly as the involved rfcs prescribe.
Some fields are accessed that often that there are support methods to provide simplified access. All these methods are called upon a message directly.
Field data can be anything, strongly dependent on the type of field at hand. If you decide to contruct the fields very carefully via some Mail::Message::Field::Full extension (like via Mail::Message::Field::Addresses objects), then you will have protection build-in. However, you can bluntly create any Mail::Message::Field object based on some data.
When you create a field, you may specify a string, object, or an array of strings and objects. On the moment, objects are only used to help the construction on e-mail addresses, however you may add some of your own.
The following rules (implemented in stringifyData()) are obeyed given the argument is:
The string must be following the (complicated) rules of the rfc2822, and is made field content as specified. When the string is not terminated by a new-line (
"\n") it will be folded according to the standard rules.
The most used Perl object to parse and produce address lines. This object does not understand character set encodings in phrases.
As part of the User::Identity distribution, this object has full understanding of the meaning of one e-mail address, related to a person. All features defined by rfc2822 are implemented.
A person is specified, which may have more than one Mail::Identity's defined. Some methods, like Mail::Message::reply() and Mail::Message::forward() try to select the right e-mail address smart (see their method descriptions), but in other cases the first e-mail address found is used.
All Mail::Identity objects in the collection will be included in the field as a group carying the name of the collection.
For all other objects, the stringification overload is used to produce the field content.
You may also specify an array with a mixture of any of the above. The elements will be joined as comma-separated list. If you do not want comma's inbetween, you will have to process the array yourself.
For performance reasons only, there are three types of fields: the fast, the flexible, and the full understander:
Fast objects are not derived from a
Mail::Reporter. The consideration is that fields are so often created, and such a small objects at the same time, that setting-up a logging for each of the objects is relatively expensive and not really useful. The fast field implementation uses an array to store the data: that will be faster than using a hash. Fast fields are not easily inheritable, because the object creation and initiation is merged into one method.
The flexible implementation uses a hash to store the data. The new() and
init methods are split, so this object is extensible.
With a full implementation of all applicable RFCs (about 5), the best understanding of the fields is reached. However, this comes with a serious memory and performance penalty. These objects are created from fast or flex header fields when study() is called.
The numeric value of a field is requested (for instance the
Content-Length fields should be numerical), however the data contains weird characters.
A new field is being created which does contain characters not permitted by the RFCs. Using this field in messages may break other e-mail clients or transfer agents, and therefore mutulate or extinguish your message.
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.
This module is part of Mail-Box distribution version 2.102, built on January 04, 2012. Website: http://perl.overmeer.net/mailbox/
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