Mail::Field(3pm) User Contributed Perl Documentation Mail::Field(3pm)
Mail::Field - Base class for manipulation of mail header fields
Mail::Field is extended by
my $field = Mail::Field->new('Subject', 'some subject text');
my $field = Mail::Field->new(Subject => 'some subject text');
print $field->tag,": ",$field->stringify,"\n";
my $field = Mail::Field->subject('some subject text');
"Mail::Field" creates and manipulates fields in MIME headers, collected
within a Mail::Header object. Different field types have their own
sub-class (extension), defining additional useful accessors to the
People are invited to merge their implementation to special fields into
MailTools, to maintain a consistent set of packages and documentation.
Mail::Field (and it's sub-classes) define several methods which return
new objects. These can all be categorized as constructor.
Take a LIST of "Mail::Field" objects (which should all be of the
same sub-class) and create a new object in that same class.
Mail::Field->extract(TAG, HEAD [, INDEX ])
Takes as arguments the tag name, a "Mail::Head" object and option-
ally 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.
Mail::Field->new(TAG [, STRING | OPTIONS])
Create an object in the class which defines the field specified by
the TAG argument.
This constructor is used internally with preprocessed field infor-
mation. When called on an existing object, its original content
will get replaced.
Parse a field line.
Change the settings (the content, but then smart) of this field.
Returns the field as a string.
Return the tag (in the correct case) for this item. Well, actually
any casing is OK, because the field tags are treated case-insenti-
tive; however people have some preferences.
Without arguments, the field is returned as stringify() does. Oth-
erwise, the STRING is parsed with parse() to replace the object's
It is more clear to call either stringify() or parse() directly,
because this method does not add additional processing.
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 ele-
ment, which should be uppercase.
o name is then created from these elements by using the first N char-
acters 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::Field"
Error: Undefined subroutine <method> called
Mail::Field objects use autoloading to compile new functionality.
Apparently, the mehod called is not implemented for the specific
class of the field object.
This module is part of the MailTools distribution, http://perl.over-
The MailTools bundle was developed by Graham Barr. Later, Mark Over-
meer took over maintenance without development.
Mail::Cap by Gisle Aas <aasAToslonett.no>. Mail::Field::AddrList by
Peter Orbaek <poeATcit.dk>. Mail::Mailer and Mail::Send by Tim Bunce
<Tim.BunceATig.uk>. For other contributors see ChangeLog.
Copyrights 1995-2000 Graham Barr <gbarrATpobox.com> and 2001-2007 Mark
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself. See
perl v5.8.8 2008-04-14 Mail::Field(3pm)