# MIME::Field::ContType

This module is ALPHA code, which means that public interfaces are largely untested, and may change in future releases. Use with caution! Please report any errors back to eryq@zeegee.com as soon as you can.

- NAME
- DESCRIPTION
- SYNOPSIS
- PUBLIC INTERFACE
- NOTES
- AUTHOR

## NAME

MIME::Field::ContType - a "Content-type" field

## DESCRIPTION

A subclass of Mail::Field.

Don't use this class directly... its name may change in the future! Instead, ask Mail::Field for new instances based on the field name!

## SYNOPSIS

        use Mail::Field;
        use MIME::Head;

        # Create an instance from some text:
        $field = Mail::Field->new('Content-type',
                                  'text/HTML; charset="US-ASCII"');

        # Get the MIME type, like 'text/plain' or 'x-foobar'.
        # Returns 'text/plain' as default, as per RFC-1521:
        my ($type, $subtype) = split('/', $field->type);

        # Get generic information:
        print $field->name;

        # Get information related to "message" type:
        if ($type eq 'message') {
    	print $field->id;
    	print $field->number;
    	print $field->total;
        }

        # Get information related to "multipart" type:
        if ($type eq 'multipart') {
    	print $field->boundary;            # the basic value, fixed up
    	print $field->multipart_boundary;  # empty if not a multipart message!
        }

        # Get information related to "text" type:
        if ($type eq 'text') {
    	print $field->charset;      # returns 'us-ascii' as default
        }

## PUBLIC INTERFACE

boundary
  Return the boundary field. The boundary is returned exactly as given in the `Content-type:` field; that is, the leading double-hyphen (`--`) is not prepended.

  (Well, almost exactly... from RFC-1521:

         (If a boundary appears to end with white space, the white space
         must be presumed to have been added by a gateway, and must be deleted.)

  so we oblige and remove any trailing spaces.)

  Returns the empty string if there is no boundary, or if the boundary is illegal (e.g., if it is empty after all trailing whitespace has been removed).

multipart_boundary
  Like `boundary()`, except that this will also return the empty string if the message is not a multipart message. In other words, there's an automatic sanity check.

type
  Try real hard to determine the content type (e.g., `"text/plain"`, `"image/gif"`, `"x-weird-type"`, which is returned in all-lowercase.

  A happy thing: the following code will work just as you would want, even if there's no subtype (as in `"x-weird-type"`)... in such a case, the $subtype would simply be the empty string:

          ($type, $subtype) = split('/', $head->mime_type);

  If the content-type information is missing, it defaults to `"text/plain"`, as per RFC-1521:

          Default RFC-822 messages are typed by this protocol as plain text in
          the US-ASCII character set, which can be explicitly specified as
          "Content-type: text/plain; charset=us-ascii".  If no Content-Type is
          specified, this default is assumed.

  Note: under the "be liberal in what we accept" principle, this routine no longer syntax-checks the content type. If it ain't empty, just downcase and return it.

## NOTES

Since nearly all (if not all) parameters must have non-empty values to be considered valid, we just return the empty string to signify missing fields. If you need to get the real underlying value, use the inherited `param()` method (which returns undef if the parameter is missing).

## AUTHOR

Eryq (eryq@zeegee.com), ZeeGee Software Inc (http://www.zeegee.com).