面向对象(object-oriented)程序设计

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• IDE的功能

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• 关注的是对象，不是流程
• 对象可以是任何东西
• 面向对象既适用于设计，也适用于实现
• 对象里封装着方法，通过接口调用，即对象等于数据和包装数据的操作
• 对象之间交互的形式是消息Objects send message
• Messages are:1.Composed by the sender 2.Interpreted by the receiver 3.Implemented by methods
• Messages may cause receiver to change state
• Messages may return results
• Class defines Object -------Object is a Class -------- cat and cat class
• OOP Characteristics

• Q:Are Messages Objects? Are Outputs Objects?

  OOP Characteristics

• Everything is an object
• A program is a bunch of objects telling each other what to so by sending messages
• Each object has its own memory made up of other objects
• Every object has a type

• All objects of a particular type can receive the same messages