Revision Notes/SOLID Principles
Field Entry - SOLID Principles
Open-Closed Principle (OCP)
Software entities should be open for extension but closed for modification — add new behavior without changing existing code.
Field Note - Real-world Analogy
“Like a power strip with sockets. The power strip (existing code) is closed for modification — you don't open it up and rewire it to support a new device. But it's open for extension — you just plug in a new device (new class) into the existing socket (interface). The strip works with any plug that fits the socket.”
Field Observations - Key Topics Covered
The idea: once a class is written and tested, you should be able to add new features to the system without going back and modifying that class. Modifying tested code is risky — you might introduce bugs in functionality that was working fine before.
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