如何從類的函數內部訪問全局變量 (How to access global variable from inside class's function)

問題描述

如何從類的函數內部訪問全局變量 (How to access global variable from inside class's function)

我有文件 init.php:

<?php 
     require_once 'config.php';
     init::load();
?>

with config.php:

<?php 
     $config = array('db'=>'abc','host'=>'xxx.xxx.xxx.xxxx',);
?>

一個名字為something.php:

<?php
     class something{
           public function __contruct(){}
           public function doIt(){
                  global $config;
                  var_dump($config); // NULL  
           }
     } 
?>

為什麼它是空的？ 在php.net中，他們告訴我我可以訪問但實際上不是。我試過但不知道。我正在使用 php 5.5.9。

參考解法

方法 1:

The variable $config in config.php is not global.

To make it a global variable, which i do NOT suggest you have to write the magic word global in front of it.

I would suggest you to read superglobal variables.

And a little bit of variable scopes.

What I would suggest is to make a class which handles you this.

That should look something like

class Config
{
    static $config = array ('something' => 1);

    static function get($name, $default = null)
    {
        if (isset (self::$config[$name])) {
            return self::$config[$name];
        } else {
            return $default;
        }
    }
}

Config::get('something'); // returns 1;

方法 2:

Use Singleton Pattern like this

<?php
     class Configs {
        protected static $_instance; 
        private $configs =[];
        private function __construct() {        
        }

        public static function getInstance() {
            if (self::$_instance === null) {
                self::$_instance = new self;   
            }
            return self::$_instance;
        }

        private function __clone() {
        }

        private function __wakeup() {
        }     
        public function setConfigs($configs){
         $this‑>configs = $configs;
        }
        public function getConfigs(){
         return $this‑>configs;
        }
    }

Configs::getInstance()‑>setConfigs(['db'=>'abc','host'=>'xxx.xxx.xxx.xxxx']);

     class Something{
           public function __contruct(){}
           public function doIt(){
                  return Configs::getInstance()‑>getConfigs();
           }
     } 
var_dump((new Something)‑>doIt());

方法 3:

Include the file like this:

 include("config.php"); 
     class something{ ..

and print the array as var_dump($config); no need of global.

方法 4:

Change your class a bit to pass a variable on the constructor.

<?php
     class something{
           private $config;
           public function __contruct($config){
               $this‑>config = $config;
           }
           public function doIt(){
                  var_dump($this‑>config); // NULL  
           }
     } 
?>

Then, if you

1. include config.php
2. include yourClassFile.php

and do,

<?php
$my_class = new something($config);
$my_class‑>doIt();
?>

It should work.

Note: It is always good not to use Globals (in a place where we could avoid them)

(by Haruji Burke、Vasil Rashkov、Alexander Gofman、Danyal Sandeelo、masterFly)

參考文件

1. How to access global variable from inside class's function (CC BY‑SA 2.5/3.0/4.0)