package AbstractClass;
sub new {
    my($class) = shift;
    bless {
        "classVar1" => undef,
        "classVar2" => undef
    }, $class;
}
sub methodOne {
    print "Error: Use of undefined Abstract Method\n";
}
sub methodTwo {
    print "Error: Use of undefined Abstract Method\n";
}

##</code><code>##

package SomeObject;
@ISA = ("AbstractClass");
sub methodOne {
    print "Doing the real function\n";
}