PHP design patterns: factory mode, singleton mode and registration mode

The three most common design patterns in all object-oriented are: factory mode, singleton mode, registration (container) mode

Factory mode, factory method or class generates objects, instead of directly new in the code

single case mode, allowing only one object of a certain class to be created

Registration mode, global sharing and exchange objects

Factory mode factory.php

<?php
class Database{
    public function __construct()
    {
        return "Database\n";
    } 
 
}
//工厂类
class Factory{
    public static function createDatabase()
    {
        $db = new Database();
        return $db;
    }
}
 
$db = Factory::createDatabase();
$db1 = Factory::createDatabase();
$db2 = Factory::createDatabase();
 
var_dump($db, $db1, $db2);
#object(Database)#1 (0) {
#}
#object(Database)#2 (0) {
#}
#object(Database)#3 (0) {
#}

Singleton mode singleton.php

<?php
//单例模式
class Database{
    protected static $db;
    //构造方法私有，防止在外层直接new
    private function __construct(){
        //code
    }
 
    static function getInstance(){
        if (self::$db) {
            return self::$db;
        }else{
            self::$db = new self();
            return self::$db;
        }
    }
}
 
$db = Database::getInstance();
$db1 = Database::getInstance();
$db2 = Database::getInstance();
 
var_dump($db, $db1, $db2);
#object(Database)#1 (0) {
#}
#object(Database)#1 (0) {
#}
#object(Database)#1 (0) {
#}

Factory mode and singleton are used together

<?php
class Database{
    protected static $db;
    private function __construct(){
        
    }
 
    static function getInstance(){
        if (self::$db) {
            return self::$db;
        }else{
            self::$db = new self();
            return self::$db;
        }
    }
}
class Factory{
    public static function createDatabase(){
        return Database::getInstance();
    }
}
 
var_dump(Factory::createDatabase());

Register class register.php

<?php
//注册器模式
class Register
{
    protected static $objects;
 
    static function set($alias, $object){
        self::$objects[$alias] = $object;
    }
    static function get($name){
        return self::$objects[$name];
    }
    function _unset($alias){
        unset(self::$objects[$alias]);
    }
}
 
Register::set(&#39;db1&#39;, $db);
Register::get(&#39;db1&#39;);

For more articles related to PHP design patterns: factory mode, singleton mode and registration mode, please pay attention to PHP Chinese website!