package MyBase;
use strict;
use Symbol 'qualify_to_ref';

sub import {
    my $class = shift;
    if (@_) {
        if ($_[0] eq '-base') {
            my (undef, %p) = @_;
            my $type = $p{is}
                or die '...';
            my $pkg = caller;

            _setup_inheritance($class => ($pkg, $type));
        }
        else {
            die '...';
        }
    }
}

sub _setup_inheritance {
    my ($class) = shift;
    my ($pkg, $type) = @_;

    $type !~ /\W/
        or die '...';

    my $method = 'is_' . $type;

    {
        my $gref = qualify_to_ref($method);
        *$gref = sub { 0 } unless defined &$gref;
    }
    {
        my $gref = qualify_to_ref($method => $pkg);
        *$gref = sub { 1 };
    }

    push @{*{qualify_to_ref(ISA => $pkg)}}, $class;

    return;
}

1;