Open Closed Principle ?(Php SOLID Principles)

During part two of our PHP Solids tutorial, we are going to go over the O in SOLID. The Open Closed Principle. This principle states that we must keep our classes open for extension but closed for modification.

To do this, we must refactor our extensible behavior behind an interface and then flip our dependencies to instead of checking the type and the executing the functionality, simply execute the functionality within the class type and enforce that the functionality exists via an interface that enforces the extensible behavior.

Come along as we dive into the Open Closed Principle and how to correctly implement it within PHP!

“When you have a class or method you want to extend without modifying it - separate the extensible behavior behind an interface, and then flip the dependencies”
~ Uncle Bob

What is the open closed principle?

"software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification"[Bertrand Meyer-1988]. That is, such an entity can allow its behavior to be modified without altering its source code.


Describe the open closed principle?
Meyer's original principle is redefined to refer to the use of interfaces, where multiple implementations could be created and polymorphically substituted for one another.
• Interface specifications are reused through inheritance; implementation need not be reused.
• The existing interface is closed to modifications and new implementations must, at a minimum, implement that interface.

https://cleancode.studio/series/solid-principles/episodes/2