# This AUTOLOAD is used to 'autoload' constants from the constant() XS function.
sub AUTOLOAD {
    my $constname;
    our $AUTOLOAD;
    ($constname = $AUTOLOAD) =~ s/.*:://;
    croak "&Blah::constant not defined" if $constname eq 'constant';
    my ($error, $val) = constant($constname);
    if ($error) { croak $error; }
    {
        no strict 'refs';
        *$AUTOLOAD = sub { $val };
    }
    goto &$AUTOLOAD;
}