Intro to Classes & Objects

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A class is more than just a code structuring mechanism; it is a blueprint for a new user-defined type. (A "type" defines how data is formatted and a set of operations allowed on that type.)

Metaphor: Blueprints and Houses

⇓ A blueprint provides a plan, but it's just a plan. To have something to live in, you have to implement the plan -- build a house.

⇓ A class provides a plan for data and a set of operations (methods ) on that data. To have actual data, you have to create (instantiate) objects (or instances) of the class.

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Advantages: Blueprints...

• allow a builder to make many copies more easily
• allow a less-experienced builder to build houses that would otherwise require more experience

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• allow builders to create complicated buildings
  

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Alyce Brady, Kalamazoo College