phpMan > man > Mail::Field(3pm)

NAME
    Mail::Field - base-class for manipulation of mail header fields

INHERITANCE
     Mail::Field is extended by
       Mail::Field::AddrList
       Mail::Field::Date
       Mail::Field::Generic

SYNOPSIS
     use Mail::Field;

     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');

DESCRIPTION
    "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 field content.

    People are invited to merge their implementation to special fields into MailTools, to maintain a
    consistent set of packages and documentation.

METHODS
  Constructors
    Mail::Field (and it's sub-classes) define several methods which return new objects. These can
    all be categorized as constructor.

    Mail::Field->combine($fields)
        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 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 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.

  "Fake" constructors
    $obj->create(%options)
        This constructor is used internally with preprocessed field information. When called on an
        existing object, its original content will get replaced.

    $obj->parse()
        Parse a field line.

  Accessors
    $obj->set(%options)
        Change the settings (the content, but then smart) of this field.

    $obj->stringify()
        Returns the field as a string.

    $obj->tag()
    Mail::Field->tag()
        Return the tag (in the correct case) for this item. Well, actually any casing is OK, because
        the field tags are treated case-insensitive; however people have some preferences.

  Smart accessors
    $obj->text( [STRING] )
        Without arguments, the field is returned as stringify() does. Otherwise, the STRING is
        parsed with parse() to replace the object's content.

        It is more clear to call either stringify() or parse() directly, because this method does
        not add additional processing.

DETAILS
  SUB-CLASS PACKAGE NAMES
    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"

DIAGNOSTICS
    Error: Undefined subroutine <method> called
        Mail::Field objects use autoloading to compile new functionality. Apparently, the method
        called is not implemented for the specific class of the field object.

SEE ALSO
    This module is part of the MailTools distribution, http://perl.overmeer.net/mailtools/.

AUTHORS
    The MailTools bundle was developed by Graham Barr. Later, Mark Overmeer took over maintenance
    without commitment to further development.

    Mail::Cap by Gisle Aas <aas AT oslonett.no>. Mail::Field::AddrList by Peter Orbaek <poe AT cit.dk>.
    Mail::Mailer and Mail::Send by Tim Bunce <Tim.Bunce AT ig.uk>. For other contributors see
    ChangeLog.

LICENSE
    Copyrights 1995-2000 Graham Barr <gbarr AT pobox.com> and 2001-2017 Mark Overmeer
    <perl AT overmeer.net>.

    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