PHP Object-oriented--final keyword class automatic loading

1.Final Keywords

Meaning: The final and final

function :

1. If a method in the parent class is declared final, the child class cannot overwrite the method.

if a class is declared final, it cannot be inherited.

2. Attributes cannot be defined as final, only classes and methods can be defined as final.

usage : Add the final keyword directly before the class or method .

---------------------------------------------------------------------------

2. automatic loading of classes

Meaning:

1. Resolve the code duplication, write the duplicate code in a folder, and let other php file calls to load automatically.

2. To solve the PHP file too many include, such as the introduction of PHP too large burden.

Implementation functions:

Spl_autoload_register () function: You can register any number of autoloader.

__autoload () : Attempting to load an undefined class classes and interfaces can also be loaded automatically (not recommended, may be deprecated). (Note: When processing a large number of programs, the program becomes bloated, cannot be implemented, the code becomes complex, which can have a significant negative impact on future system maintenance and system efficiency)

Note : Auto-load is not available for PHP's CLI interaction mode .

PHP Load File mode:
1, include,include_once,requice,requice_one Regular loading
2, __autoload ()
3, Spl_autoload_register ()

__autoload () Auto Load

<?php  function __autoload( $class ){     $file = $class . ‘.php‘ ;//拼接路径     if ( is_file ( $file )) { //判断$file是否存在      require_once ( $file ); //从$file路径导入一次    }  }  $a = new A(); Note: Because __autoload () is a function, it can only exist once. ----------------------------------------------------------------------------- spl_autoload_register () Auto LoadSpl_autoload_register () It actually creates a queue of autoload functions, executed one by one, in the order they were defined. In contrast, __autoload () can be defined only once. <?php  function loader( $class ){     $file = $class . ‘.php‘ ;     if ( is_file ( $file )) {       require_once ( $file );     }  }  spl_autoload_register( ‘loader‘ );  $a = new A();Use anonymous functions directly: <?php    spl_autoload_register( function ( $file ){    $file = $class . ‘.php‘ ;     if ( is_file ( $file )) {       require_once ( $file );     } });  $a = new A();

This can also work properly, when PHP is looking for classes without calling __autoload instead of calling our own defined function loader. In the same way, the following is also possible:

12345678910111213

<?php  class Loader {    public static function loadClass($class){      $file = $class . ‘.php‘;      if (is_file($file)) {        require_once($file);      }    }  }  spl_autoload_register(array(‘Loader‘, ‘loadClass‘)); //spl_autoload_register(array(__CLASS__, ‘loadClass‘)); //spl_autoload_register(array($this, ‘loadClass‘)); $a = new A();

PHP Object-oriented--final keyword class automatic loading