What are the principles of software design (OCP)

Article transferred from What is software design (OCP) principle _shanglizhangrui The column -CSDN Blog

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When designing a module , The module should be extended without modification .

（1） Open to expansion
That is, when you want to expand the function , There is no need to change the internal code block , It can be extended directly ;
（2） Changes are closed
When extending a module , The internal code does not need to be changed .