idea

There are three types of extensibility:

Vertical, that extend the type hierarchy. In OOP, that corresponds to adding to the existing types. In product, that's extending the feature set.
Horizontal, that extends the spectrum of operations available on a type. In OOP, that's adding methods to a specific type. In product, that's adding components to a certain feature.
Behavioral, that extends or modifies the original behavior of operations. In OOP, that's modifying the behavior of a feature. In product, that's modifying a specific feature.

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[[composition-over-extension]]