Composition vs. Aggregation

Composition vs. Aggregation: The Has-A Relationship, Explained Simply

A calm, thorough guide to the difference between composition and aggregation in object-oriented design: the backpack-and-library-book analogy, association as the parent concept (with multiplicity, one-directional and two-directional links, and the UML 1990s origin story), aggregation as the loose has-a relationship (independent lifecycle, shareable parts, School-and-Teacher example), composition as the strict…

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What Is Polymorphism Used For in Real Architecture?

What Is Polymorphism Used For in Real Architecture?

A calm, thorough guide to how polymorphism shows up in real, professional software architecture: the play-button and TV-remote analogies, what polymorphism really means (many forms, one shared instruction, substitutability), the two main types (compile-time / runtime) plus the extras (parametric, coercion), method overloading and operator overloading, method overriding and the…

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Composition Over Inheritance

Composition Over Inheritance

A gentle, thorough guide to one of the most useful ideas in software design: the box-of-clip-together-blocks vs. pre-molded-figure analogy, what inheritance really gives you (code reuse, polymorphism, specialization), what composition really is (holding and delegating), the two flavors composition/aggregation, the is-a vs has-a sentence test with the classic Penguin/FlyingBird and…

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