Analysis of PHP Late Static Binding Instance

This article illustrates the late static binding of PHP. Share it for your reference, as follows:

Beginning with php 5.3, php added a feature called late binding to reference statically called classes within the scope of inheritance

This function is named "late static binding" from the perspective of language interior; "Late binding" means: static:: It is no longer parsed to define the class where the current method is located, but calculated at actual runtime, and can also become "static binding"; Because it can be used (but not limited to static method calls).

Limitations of self::

Use self:: Or _class_ Static reference to the current class, depending on the class in which the current method is defined

Examples:

class A {
  public static function who() {
    echo __CLASS__;
  }
  public static function test() {
    self::who();
  }
}
class B extends A {
  public static function who() {
    echo __CLASS__;
  }
}
B::test(); //A

Print results:

A

Usage of late static binding

Late static binding attempts to bypass the restriction by introducing a keyword to represent the class originally called at runtime. Simply put, this keyword allows you to refer to B instead of A when you call test () above. It was finally decided not to reference the new keyword, but to use the reserved static keyword

Examples:

<?php
class A {
  public static function who() {
    echo __CLASS__;
  }
  public static function test() {
    static::who(); //  Late static binding starts here 
  }
}
class B extends A {
  public static function who() {
    echo __CLASS__;
  }
}
B::test();
?>

The printed result is:

B

The processing method of late static binding solves the static call which has not been solved completely in the past. In the other aspect, if the static call uses parent:: or self::, the call information will be forwarded

<?php
class A {
  public static function foo() {
    static::who();
  }
  public static function who() {
    echo __CLASS__."\n";
  }
}
class B extends A {
  public static function test() {
    A::foo();
    parent::foo();
    self::foo();
  }
  public static function who() {
    echo __CLASS__."\n";
  }
}
class C extends B {
  public static function who() {
    echo __CLASS__."\n";
  }
}
C::test();
?>

Print results:

A
C
C

Examples:

<?php
class a {
 static public function test() {
  print get_called_class();
 }
}
class b extends a {
}
a::test();
b::test();
?>

Print results:

a
b

Special statement:

get_called_class() ; Get the name of the class. Call in the static method

For more readers interested in PHP related content, please check the topics on this site: "Introduction to php Object-Oriented Programming", "Encyclopedia of PHP Array (Array) Operation Skills", "Introduction to PHP Basic Grammar", "Summary of PHP Operation and Operator Usage", "Summary of php String (string) Usage", "Introduction to php+mysql Database Operation" and "Summary of php Common Database Operation Skills"

I hope this article is helpful to everyone's PHP programming.