You'll never reach true Open Closed nirvana, but you can inch much closer by rigorously following the related Single Responsibility Principle: a class should have one, and only one, reason to change

你永远也达不到真正的开闭天堂，但是通过严格地遵循与之相关的单一责任原则：一个类应该有并且只有一个更改的理由，你可以非常靠近地接近它。

youdao