Pat Maddox's example from Streamlined Object Modeling

gistfile1.java

# http://tech.groups.yahoo.com/group/domaindrivendesign/message/6654

class Target {
  public void strike(missile) {
    missile.setCoordinates(self.coordinates);
    missile.launch();
    markDestroyed();
  }
}

class PatsHouse extends Target {
  public void strike(missile) {
    raise new BadIdeaError("Whoa whoa who, I don't want to die");
  }
}

as opposed to the Missile class being invasive:

class Missile {
  public void strike(target) {
    setCoordinates(target.coordinates);
    launch();
    target.markDestroyed();
  }
}