sub _onmatch_fail
{
    my ( $self, $_codetext, $_valhref, $_taskname ) = @_;

    my $FAIL_MATCH = 0;                                            # match defaults to succeed
    my $_codetext  = "# line 1 task[$_taskname]\n" . $_codetext;

    {
        use Alias qw(attr);

        attr $_valhref;
        no Alias;

        no warnings qw(once);
        no strict qw(vars);

        eval $_codetext;
        die $@ if $@;

        return $FAIL_MATCH;
    }
}