MIME::Expander - Walks through all the MIME parts expanded recursively in a message


    use MIME::Expander;
    use IO::All;
    my $callback = sub {
            my $em = shift; # is instance of Email::MIME
            $em->body > io( $em->filename );
    my $exp = MIME::Expander->new;
    my $num = $exp->walk( io($ARGV[0])->all, $callback );
    print "total $num files are expanded.\n";


MIME::Expander is an utility module that works like the Email::MIME::walk method. Feature of this module is that all the parts passing to the callback, are expanded by MIME mechanism. It expands archived, compressed or multi-parted message using various MIME::Expander::Plugin modules.


The constructor new() accepts a reference of hash as configurations.

Following key of hash are available, and there is an access method of a same name.


A value is a list reference and the elements are string or regular expression.

If this parameter is set, then the walk() will not expand contents of specified mime types.


A value is a reference of code or reference of array which contains name of the "guess classes". In the case of a code, it is only performed for determining the mime type. In array, it performs in order of the element, and what was determined first is adopted.

Each routines have to determine the type of the data which will be inputted.

The parameters passed to a routine are a reference of scalar to contents, and information as reference of hash.

Although the information may have a "filename", however depending on implements of each expander module, it may not be expectable.

The routine have to return mime type string, or undef. If value of return is false value, that means "application/octet-stream".

For example, sets routine which determine text or jpeg.

    my $exp = MIME::Expander->new({
        guesser => sub {
                my $ref_contents = shift;
                my $info         = shift || {};
                if( defined $info->{filename} ){
                    my ($suffix) = $info->{filename} =~ /\.(.+)$/;
                    if( defined $suffix ){
                        if( lc $suffix eq 'txt' ){
                            return 'text/plain';
                        }elsif( $suffix =~ /^jpe?g$/i ){
                            return 'image/jpeg';

When useing the "guess classes", like this is the default of guesser, package name is omissible:

    my $exp = MIME::Expander->new({
        guesser => [qw/MMagic FileName/],

Please look in under namespace of MIME::Expander::Guess about what kinds of routine are available.


A value is a native number.

Please see "walk".


regulate_type( $type )

Simplify when the type which removed "x-" is registered.

    MIME::Expander->regulate_type("text/plain; charset=ISO-2022-JP");
    #=> "text/plain"

    #=> "application/tar"

Please see about "simplified" in the document of MIME::Type.



Initialize instance. This is for overriding.

expects( \@list )

Accessor to field "expects".

is_expected( $type )

Is $type the contents set to field "expects" ?

depth( $native_number )

Accessor to field "depth".

guesser( \&code | \@list )

Accessor to field "guesser".

guess_type_of( \$contents, [\%info] )

Determine mime type from the $contents.

Optional %info is as hint for determing mime type. It will be passed to "guesser" directly.

A key "filename" can be included in %info.

plugin_for( $type )

Get an instance of the expander class for mime type "$type".

    my $me = MIME::Expander->new;
    my $expander = $me->plugin_for('application/tar') or die "not available";
    $expander->expand( \$data, $callback );

Please see also the PLUGIN section.

create_media( \$contents )

Create an instance of Email::MIME from $contents. If $contents does not look like a valid syntax of email, it is as an attachment.

walk( \$message, $callback )

Walks through all the MIME parts expanded recursively in a $message. If the $message includes expandable contents, the callback will accept each MIME parts as instance of Email::MIME. Or $message does not have parts, the callback will accept $message own.

See also Email::MIME about $email object.

Note that the expanded data are further checked and processed recursively. And the recursive depth is to the level of the value of "depth" field.


Expanding module for expand contents can be added as plug-in.

Please see MIME::Expander::Plugin for details.


This module implements in-memory decompression.


MIME::Expander is hosted on github


WATANABE Hiroaki <>


This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.