goals.py

class Goal(object):
    name = 'Generic Goal'
    
    @classmethod
    def getConcreteClasses(cls):
        for c in cls.__subclasses__():
            yield c
            for c2 in c.getConcreteClasses():
                yield c2

    def progress(self):
        return self.completed / self.total
    

class InfluenceGoal(Goal):
    name = 'Influence Goal'

    def progress(self):
        return self.completed / self.total