策略模式如何运作？ [英] How does the Strategy Pattern work?

问题描述

$ p

How does it work, what is it used for and when should one use it?

推荐答案

我们来解释一下策略模式简单的方法：

Let's explain the strategy pattern the easy way:

您有一个类 Car（），方法 run ），所以你以伪语言这样使用：

You have a class Car() with a method run(), so you use it this way in a pseudo language:

mycar = new Car()
mycar.run()

现在，您可能需要更改<$ c $当程序正在执行时，c> run（）行为。例如，您可能需要模拟电机故障或在视频游戏中使用boost按钮。

Now, you may want to change the run() behavior on the fly, while the program is executing. For example, you might want to simulate a motor failure or the use of a "boost" button in a video game.

有几种方法可以进行此模拟：使用条件语句和标志变量是一种方法。策略模式是另一个：它将 run（）方法的行为委托给一个子类：

There are several ways to do this simulation: using conditional statements and a flag variable is one way. The strategy pattern is another: it delegates the behavior of the run() method to a subclass:

Class Car()
{
    this.motor = new Motor(this) 

    // passing "this" is important for the motor so it knows what it is running

    method run()
    {
        this.motor.run()
    }

    method changeMotor(motor)
    {
        this.motor = motor 
    }

}

如果你想改变汽车的行为，你可以改变电机。 （在一个程序中，在现实生活中更容易，对吗？;-)）

If you want to change the car's behavior, you can just change the motor. (Easier in a program then in real life, right? ;-) )

如果你有很多复杂的状态，这是非常有用的：你可以改变和维护他们更容易。

It's very useful if you have a lot of complex states: you can change and maintain them much more easily.

这篇关于策略模式如何运作？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！