Understanding PHP interfaces and abstractions_PHP tutorial-PHP Tutorial-php.cn

Understanding PHP interfaces and abstractions_PHP tutorial

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Release： 2016-07-13 10:33:19

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A little brother asked me today, what are the uses of interface classes and abstract classes in PHP? He doesn’t know how to use them at all, and thinks there is no point in using them. In fact, he has the same idea. When I first came into contact with PHP, I felt that this thing was of little use. After gradually coming into contact with large systems, I discovered that these things actually have a certain effect. I will briefly talk about it below.

php interface class: interface

In fact, their role is very simple. When many people develop a project together, they may all call some classes written by others. Then you may ask, how do I know how to name the implementation method of a certain function? Well, at this time the php interface class comes into play. When we define an interface class, the methods in it must be implemented by the following subclasses, such as

interface Shop
{
	public function buy($gid);
	public function sell($gid);
	public function view($gid);
}

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I declare a shop interface class and define three methods: buy, sell, and view. Then all subclasses that inherit this class must implement any of these three methods. , if the subclass does not implement these words, it will not run. In fact, the interface class is, to put it bluntly, the template of a class and the regulations of a class. If you belong to this category, you must follow my regulations. No matter how you do it, I don’t care how you do it. That’s up to you. things, such as:

class BaseShop implements Shop
{
	public function buy($gid)
	{
		echo '你购买了ID为 :' . $gid . '的商品';
	}
    
	public function sell($gid)
	{
		echo '你购卖ID为 :' . $gid . '的商品';
	}
    
	public function view($gid)
	{
		echo '你浏览了ID为 :' . $gid . '的商品';
	}
}

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Think about it, in a large project where many people collaborate, it is very convenient to have interface classes, so that you don’t have to ask others what the method name of your certain function is. Of course, if you like There's nothing I can do about it.

Conclusion: The interface class is the leader of a class, pointing out the direction, and the subclass must complete its specified method.

php abstract class: abstract

In fact, abstract classes and interface classes are partially similar. I remember seeing this sentence somewhere, abstract classes extract the part of the class image. This sentence looks funny, but in fact it tells the truth of abstract classes. The role of abstract classes is that when you find that many of your classes use many methods that you keep rewriting, then you can consider using abstract classes. You may say, "I can't rewrite one class for every public class." I just instantiate this public class and call the same method." This is possible. In fact, this is what the abstract class does, but it saves you the step of instantiation, allowing you to directly It is just as convenient to call this class method, and you can also overload this method. Such as:

abstract class BaseShop 
{
	public function buy($gid)
	{
		echo '你购买了ID为 :' . $gid . '的商品';
	}
    
	public function sell($gid)
	{
		echo '你购卖ID为 :' . $gid . '的商品';
	}
    
	public function view($gid)
	{
		echo '你浏览了ID为 :' . $gid . '的商品';
	}
}
class BallShop extends BaseShop
{
	var $itme_id = null;
	public function __construct()
	{
		$this->itme_id = 2314;
	}
    
	public function open()
	{
		$this->sell($this->itme_id);
	}
}

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Here is an example. Like the above, I defined a store class and extracted all its parts, such as buy, sell, and view, and all of these are implemented in the abstract class. methods, then the subclass that inherits it will automatically obtain these methods, and the subclass will do its own unique things, introduce duplication of code, and improve reusability.

Conclusion: An abstract class is a service provider of a class. It has many services. You don’t have to use them. You can use them when needed. If you feel dissatisfied with not providing services, you can do it yourself.

The above are my humble opinions on PHP interface classes and abstract classes. I hope it can help those who are confused about these two.