C++之 面向对象基本原理

Object Oriented Programming

• Objects send and receive messages(objects do things!)

Objects send messages

• Messages are

-Composed by the sender

-Interpreted by the receiver//kouyi

-Implemented by methods//shishi

• Messages
• May cause receiver to change state

• May return results

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Object vs. Class

Object (cat)

Represent things,events, or concepts

Respond to messages at run-time 

Classes(cat class)

Define properties of instances

Act like types in C++

OOP Characteristics

1.Everything is an object.

2.A program is a bunch of objects telling each other what to do by sending messages.

3.Each object has its own memory made up of other objects.

4.Every object has a type.

5.All objects of a particular type can receive the same messages.//正反理解

 

An object has an interface

The interface is the way it receives messages.

It is defined in the class the object belong to.

 

Functions of the interface

• Communication
• Protection

The Hidden Implementation

• Inner part of an object,data menbers to present its state,and the actions it takes when messages is rcvd id hidden.
• Class creators vs. Client programmers

-Keep client programmers' hands off portions they shoule not touch.

-Allow the class creators to change the internal working of the class without worrying about how it will affect the client programmers.

Encapsulation//封装

• Bundle data and methods dealing with these data together in an object
• Hide the details if the data and the action
• Restrict only access to the publicized methods.