Mail::Field - phpMan

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