MAIL/FIELD(1)          User Contributed Perl Documentation         MAIL/FIELD(1)

       Mail::Field - Base class for manipulation of mail header fields

           use Mail::Field;

           $field = Mail::Field->new('Subject', 'some subject text');
           print $field->tag,": ",$field->stringify,"\n";

           $field = Mail::Field->subject('some subject text');

       Mail::Field is a base class for packages that create and manipulate
       fields from Email (and MIME) headers. Each different field will have its
       own sub-class, defining its own interface.

       This document describes the minimum interface that each sub-class should
       provide, and also guidlines on how the field specific interface should be

       Mail::Field, and it's sub-classes define several methods which return new
       objects. These can all be termed to be constructors.

       new ( TAG [, STRING ⎪ OPTIONS ] )
           The new constructor will create an object in the class which defines
           the field specified by the tag argument.

           After creation of the object :-

           If the tag argument is followed by a single string then the parse
           method will be called with this string.

           If the tag argument is followed by more than one arguments then the
           create method will be called with these arguments.

       extract ( TAG, HEAD [, INDEX ] )
           This constuctor takes as arguments the tag name, a Mail::Head object
           and optionally an index.

           If the index argument is given then extract will retrieve the given
           tag from the Mail::Head object and create a new Mail::Field based
           object.  undef will be returned in the field does not exist.

           If the index argument is not given the the result depends on the
           context in which extract is called. If called in a scalar context the
           result will be as if extract was called with an index value of zero.
           If called in an array context then all tags will be retrieved and a
           list of Mail::Field objects will be returned.

       combine ( FIELD_LIST )
           This constructor takes as arguments a list of Mail::Field objects,
           which should all be of the same sub-class, and creates a new object
           in that same class.

           This constructor is nor defined in Mail::Field as there is no generic
           way to combine the various field types. Each sub-class should define
           its own combine constructor, if combining is possible/allowed.





       All sub-classes should be called Mail::Field::name where name is derived
       from the tag using these rules.

       ·   Consider a tag as being made up of elements separated by '-'

       ·   Convert all characters to lowercase except the first in each element,
           which should be uppercase.

       ·   name is then created from these elements by using the first N
           characters from each element.

       ·   N is calculated by using the formula :-

               int((7 + #elements) / #elements)

       ·   name is then limited to a maximum of 8 characters, keeping the first
           8 characters

       For an example of this take a look at the definition of the
       _header_pkg_name subroutine in Mail::Field

       Graham Barr <>

       $Revision: 1.2 $

       The revision and the VERSION are not the same but the VERSION is derived
       from the revision number. This is because the revision number is not a
       real number. The method used for doing this is to turn each number after
       the first period into a 2 digit number with leading zeros and then
       removing all but the first period. For example

               Revision 1.8   => VERSION 1.08
               Revision 1.2.3 => VERSION 1.0203

       the MIME::* manpages

       Eryq <> - for all the help in defining this
       package so that Mail::* and MIME::* can be integrated together.

       Copyright (c) 1995 Graham Barr. All rights reserved. This program is free
       software; you can redistribute it and/or modify it under the same terms
       as Perl itself.

3rd Berkeley Distribution        perl 5.003 with                   MAIL/FIELD(1)