ch 8

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The Liskov substitution Principle lsp

lsp is all about well-organized & well-designed inheritance. when you inherit from a base class, you must be able to substitute your subclass.

• It's all about substitution.

• LSP reveals problems about inheritance.

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Composition

Composition is most powerful when you want to use behavior to be defined in an interface.

• It allows you to use behavior from a family of other classes, and to chang that behavior at the runtime.

• When an objects composed of other objects and that owing object is destroyed, the obj that are pert of the composition go away too.

• Composition is about ownership. the main obj owns the composed behavior.

Aggregation

Aggregation is used when one class ia used as a part of another class, yet still exists outside of that other class

• It's a variation in composition.

Aggregation VS Composition -- look at pg 430 and 431.