Detailed explanation of PHP delayed static binding static

In the old version of PHP, return new self() is used to return an instance of this class; but this method has a big drawback, that is, self refers to the parsing context rather than the calling context. This article mainly shares with you the detailed explanation of PHP delayed static binding static. I hope it can help you.

abstract class father { 

    public static function create() { 

        return new self(); 

    } 
} 
class son1 extends father { 
} 
son1::create();

That is to say, the subclass calling the create() method in the above code actually returns an instance of the parent class, because self points to the place where it is defined rather than the place where it is called, and father If the class is an abstract class, this code will report a fatal error.

Delayed static binding was introduced after PHP5.3, using the static keyword.


abstract class father { 

    public static function create() { 

        return new static(); 

    } 
} 
class son1 extends father { 
} 
son1::create();

Change self to static and it will execute normally, because static points to the called class rather than the defined class.

We can also use static as the identifier of a static method, even when called from a non-static context. I’ll write about this later.

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