Chapter 9

To start with, I'll define the back end XSUBs in a separate package using the 

PACKAGE command on the MODULE line:

MODULE = Gnome::MIME   PACKAGE = Gnome::MIME::Backend   PREFIX = gnome_mime_

After this line every XSUB defined will have its Perl interface defined in the 

Gnome::MIME::Backend package. An XS file can contain any number of such 

lines and PACKAGEs, although only one MODULE may be used.

Then each of the functions is wrapped in the plain style shown earlier:

const char *

gnome_mime_type(filename)

  char * filename

const char *

gnome_mime_type_or_default(filename, default)

  char * filename

  char * default

const char *

gnome_mime_type_of_file(filename)

  char * filename

const char *

gnome_mime_type_of_file_or_default(filename, default)

  char * filename

  char * default

The Perl code to implement the named parameter interface is then added to 

MIME.pm:

use Carp qw(croak);

sub file_type {

  croak("Usage: Gnome::MIME::file_type(k => v, ...)") if @_ % 2;

  my %args = @_;

  # check for bad parameter names

  my %allowed = map { $_, 1 } qw(filename default_type read_file);

  for (keys %args) {

    croak("Unknown key found in Gnome::MIME::file_type parameter list: $_")

      unless exists $allowed{$_};

  }

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