Mail::Field(3) User Contributed Perl Documentation Mail::Field(3)NAMEMail::Field - Base class for manipulation of mail header
fields
SYNOPSIS
use Mail::Field;
$field = Mail::Field->new('Subject', 'some subject text');
print $field->tag,": ",$field->stringify,"\n";
$field = Mail::Field->subject('some subject text');
DESCRIPTIONMail::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 defined.
CONSTRUCTOR
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
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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.
METHODS
parse
set
tag
stringify
SUB-CLASS PACKAGE NAMES
All sub-classes should be called Mail::Field::name where
name is derived from the tag using these rules.
o Consider a tag as being made up of elements separated
by '-'
o Convert all characters to lowercase except the first
in each element, which should be uppercase.
o name is then created from these elements by using the
first N characters from each element.
o N is calculated by using the formula :-
int((7 + #elements) / #elements)
o 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::FieldAUTHOR
Graham Barr <gbarr@pobox.com>
SEE ALSO
the MIME::* manpages
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Mail::Field(3) User Contributed Perl Documentation Mail::Field(3)CREDITS
Eryq <eryq@rhine.gsfc.nasa.gov> - for all the help in
defining this package so that Mail::* and MIME::* can be
integrated together.
COPYRIGHT
Copyright (c) 1995-7 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.
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