MIME::Field::ParamVal - phpMan

NAME
    MIME::Field::ParamVal - subclass of Mail::Field, for structured MIME
    fields

SYNOPSIS
        # Create an object for a content-type field:
        $field = new Mail::Field 'Content-type';

        # Set some attributes:
        $field->param('_'        => 'text/html');
        $field->param('charset'  => 'us-ascii');
        $field->param('boundary' => '---ABC---');

        # Same:
        $field->set('_'        => 'text/html',
                    'charset'  => 'us-ascii',
                    'boundary' => '---ABC---');

        # Get an attribute, or undefined if not present:
        print "no id!"  if defined($field->param('id'));

        # Same, but use empty string for missing values:
        print "no id!"  if ($field->paramstr('id') eq '');

        # Output as string:
        print $field->stringify, "\n";

DESCRIPTION
    This is an abstract superclass of most MIME fields. It handles fields
    with a general syntax like this:

        Content-Type: Message/Partial;
            number=2; total=3;
            id="oc=jpbe0M2Yt4s AT thumper.com"

    Comments are supported *between* items, like this:

        Content-Type: Message/Partial; (a comment)
            number=2  (another comment) ; (yet another comment) total=3;
            id="oc=jpbe0M2Yt4s AT thumper.com"

PUBLIC INTERFACE
    set [\%PARAMHASH | KEY=>VAL,...,KEY=>VAL]
        *Instance method.* Set this field. The paramhash should contain
        parameter names in *all lowercase*, with the special "_" parameter
        name signifying the "default" (unnamed) parameter for the field:

           # Set up to be...
           #
           #     Content-type: Message/Partial; number=2; total=3; id="ocj=pbe0M2"
           #
           $conttype->set('_'       => 'Message/Partial',
                          'number'  => 2,
                          'total'   => 3,
                          'id'      => "ocj=pbe0M2");

        Note that a single argument is taken to be a *reference* to a
        paramhash, while multiple args are taken to be the elements of the
        paramhash themselves.

        Supplying undef for a hashref, or an empty set of values,
        effectively clears the object.

        The self object is returned.

    parse_params STRING
        *Class/instance utility method.* Extract parameter info from a
        structured field, and return it as a hash reference. For example,
        here is a field with parameters:

            Content-Type: Message/Partial;
                number=2; total=3;
                id="oc=jpbe0M2Yt4s AT thumper.com"

        Here is how you'd extract them:

            $params = $class->parse_params('content-type');
            if ($$params{'_'} eq 'message/partial') {
                $number = $$params{'number'};
                $total  = $$params{'total'};
                $id     = $$params{'id'};
            }

        Like field names, parameter names are coerced to lowercase. The
        special '_' parameter means the default parameter for the field.

        NOTE: This has been provided as a public method to support backwards
        compatibility, but you probably shouldn't use it.

    parse STRING
        *Class/instance method.* Parse the string into the instance. Any
        previous information is wiped. The self object is returned.

        May also be used as a constructor.

    param PARAMNAME,[VALUE]
        *Instance method.* Return the given parameter, or undef if it isn't
        there. With argument, set the parameter to that VALUE. The PARAMNAME
        is case-insensitive. A "_" refers to the "default" parameter.

    paramstr PARAMNAME,[VALUE]
        *Instance method.* Like param(): return the given parameter, or
        *empty* if it isn't there. With argument, set the parameter to that
        VALUE. The PARAMNAME is case-insensitive. A "_" refers to the
        "default" parameter.

    stringify
        *Instance method.* Convert the field to a string, and return it.

    tag *Instance method, abstract.* Return the tag for this field.

SEE ALSO
    Mail::Field