在PHP中使用普通函数和类方法有什么区别? [英] What's the difference between using normal functions and class methods in PHP?

问题描述

我正在尝试学习如何在PHP中最好地使用OOP.请注意，即使我研究了这个新的世界"的理论，我显然也没有进入OOP思维.

I'm trying to learn how to best use OOP in PHP. Please be aware that even if I studied the theory of this new "world" I didn't enter the OOP thinking yet obviously.

使用普通的分离函数并将它们作为方法放在类中有什么区别?

What's the difference between using normal, separated functions and putting them in a class as methods?

比方说，我有一堂课叫做商店".

Let's say I have a class called "shop".

它具有以下方法:检索项，删除项，更新项，添加项

It has these methods: retrieveitems, deleteitems, updateitems, additems

除了我可以使用简单的"$ this"在方法内部调用方法外，将它们放入没有类的不同函数之间有什么区别?我的意思是，例如，我仍然可以在函数retrieveitems中调用函数deleteitems，对吗?即使不在课堂上?

Except for the fact that I can call methods inside methods with a simple "$this", what is the difference between putting them in different functions without a class? I mean, for example, I still can call function deleteitems inside function retrieveitems right? Even if not in a class?

请帮助我了解我所缺少的内容.

Please help me understand what I'm missing.

推荐答案

OOP提供了封装功能.

OOP provides, among other things, encapsulation.

class Shop {

    function __construct($items) {
        $this->inventory = $items;
    }

    function deleteItem($item) {
        $key = array_search($item, $this->inventory);
        if ($key !== false)
            unset($this->inventory[$key]);
    }

}

现在您可以创建实例:

$computerShop  = new Shop(array('ram', 'monitor', 'cpu', 'water'));
$hardwareStore = new Shop(array('hammer', 'screwdriver', 'water'));

他们每个人都是彼此独立的.如果我执行$computerShop->removeItem('water')，则$hardwareStore的inventory中仍应包含water. (看到实际效果.)执行此过程的方法更加麻烦.

And each one of them is independent from each other. If I do $computerShop->removeItem('water'), $hardwareStore should still have water in their inventory. (see it in action) Doing this the procedural way is much messier.

关于OOP的另一个有趣的事情是，您可以使用继承和多态性:

Another cool thing about OOP is that you can use inheritance and polymorphism:

class Animal {

    function eat() {
        $this->hungry = false;
    }

    abstract function speak();
}

class Cat extends Animal {

    function speak() {
        echo 'meow!';
    }
}

class Dog extends Animal {

    function speak() {
        echo 'woof!';
    }    
}

现在，即使Cat和Dog都未在其类中明确声明，也可以调用方法eat()-它是从其父类Animal继承的.他们还具有speak()方法，可以执行不同的操作.很好，是吧?

Now both Cat and Dogs can call the method eat() even though they are not explicitly declared in their classes - it's been inherited from their parent class Animal. They also have a speak() method that does different things. Pretty neat, huh?

面向对象的编程，多态

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