Introduction to the late static binding function of PHP object-oriented

This article will introduce the late static binding function of PHP, which is mainly used to solve the problem of referencing statically called classes in the inheritance scope.

First look at the following example:

class Person
{
 
    public static function status()
    {
        self::getStatus();
    }
 
    protected static function getStatus()
    {
        echo "Person is alive";
    }
 
}
 
class Deceased extends Person
{
 
    protected static function getStatus()
    {
        echo "Person is deceased";
    }
 
}
 
Deceased::status(); //Person is alive

Obviously, the result is not what we expected. This is because self:: depends on the class in which it is defined, not the running class. In order to solve this problem, you may override the status() method in the inherited class. A better solution is that PHP 5.3 added the function of late static binding.

class Person
{
 
    public static function status()
    {
        static::getStatus();
    }
 
    protected static function getStatus()
    {
        echo "Person is alive";
    }
 
}
 
class Deceased extends Person
{
 
    protected static function getStatus()
    {
        echo "Person is deceased";
    }
 
}
 
Deceased::status(); //Person is deceased

It can be seen that static:: no longer points to the current class. In fact, it is calculated at runtime, forcing all properties of the final class to be obtained.

Therefore, it is recommended that you do not use self:: and use static:: in the future.

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