Example ABC

strategy.py

#!/usr/bin/env python
from abc import ABCMeta, abstractmethod

class StorageStrategy(metaclass=ABCMeta):
    @abstractmethod
    def printSomething(self, something):
        pass

class MongoDBStorageStrategy(StorageStrategy):
    def printSomething(self, something):
        print(something)

class RunStorageStrategy():
    def __init__(self, strategy):
        if strategy == "MongoDB":
            self.cls = MongoDBStorageStrategy()

    def runStrategy(self):
        self.cls.printSomething("hello, world")

def main():
    strategy = RunStorageStrategy("MongoDB")
    strategy.runStrategy()

if __name__ == "__main__":
    main()