A brief analysis of the difference between static and self in PHP classes

Use self:: or __CLASS__ to get a static reference to the current class, depending on the class in which the method is defined:

Using static:: is no longer resolved to the class where the current method is defined, but is actually calculated at runtime. It can also be called "static binding" because it can be used for (but is not limited to) calling static methods.

Static binding is a feature added in PHP 5.3.0 that is used to reference statically called classes in the inheritance scope.

The difference between static and self in PHP classes. We often see self and static in the definition of PHP classes. When running, we often find that the results are no different, but there is definitely a difference. If there is no difference, why are there two?

1. The difference between the two

Static uses delayed binding

Therefore, static can accurately know whether it is a call from the parent class or the child class.

For example, this shows that Static is a smart kid. He can accurately recognize all his relatives.

Self is a little bit stupid, he only knows your own parents

2. Code looks different

It can be seen from the following code

self refers to the class that defines him, that is, he only knows his own parents

static refers to the class that calls him, that is, he can recognize his relatives

<?php
class parents
{
    protected static $name = 'I am your parent';
 
    public static function who_self()
    {
        return self::$name;
    }
 
    public static function who_static()
    {
        return static::$name;
    }
 
    public static function get_self()
    {
        return new self();
    }
 
    public static function get_static()
    {
        return new static();
    }
}
 
class kinsfolk extends parents
{
    protected static $name = 'I am your relative';
}
 
var_dump(kinsfolk::who_self()); //I am your parentvar_dump(kinsfolk::who_static()); //I am your relativevar_dump(kinsfolk::get_self()); //object(parents)#1 (0) {}
var_dump(kinsfolk::get_static()); //object(kinsfolk)#1 (0) {}

In simple terms,

Self is the class in which it is written, and this class is actually called.

static represents the class being used, that is, the static you wrote in the parent class, and then it is overwritten by the subclass, and the method or attribute of the subclass is used

Summarize

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