How to write a lightweight container in php

class Di implements \ArrayAccess{  
    private $_bindings = array();//服务列表  
    private $_instances = array();//已经实例化的服务  
      
    //获取服务  
    public function get($name,$params=array()){  
        //先从已经实例化的列表中查找  
        if(isset($this->_instances[$name])){  
            return $this->_instances[$name];  
        }  
          
        //检测有没有注册该服务  
        if(!isset($this->_bindings[$name])){  
            return null;  
        }  
          
        $concrete = $this->_bindings[$name]['class'];//对象具体注册内容  
          
        $obj = null;  
        //匿名函数方式  
        if($concrete instanceof \Closure){  
            $obj = call_user_func_array($concrete,$params);  
        }elseif(is_string($concrete)){//字符串方式  
            if(empty($params)){  
                $obj = new $concrete;  
            }else{  
                //带参数的类实例化，使用反射  
                $class = new \ReflectionClass($concrete);  
                $obj = $class->newInstanceArgs($params);  
            }  
        }  
          
        //如果是共享服务，则写入_instances列表，下次直接取回  
        if($this->_bindings[$name]['shared'] == true && $obj){  
            $this->_instances[$name] = $obj;  
        }  
          
        return $obj;  
    }  
      
    //检测是否已经绑定  
    public function has($name){  
        return isset($this->_bindings[$name]) or isset($this->_instances[$name]);  
    }  
      
    //卸载服务  
    public function remove($name){  
        unset($this->_bindings[$name],$this->_instances[$name]);  
    }  
      
    //设置服务  
    public function set($name,$class){  
        $this->_registerService($name, $class);  
    }  
      
    //设置共享服务  
    public function setShared($name,$class){  
        $this->_registerService($name, $class, true);  
    }  
      
    //注册服务  
    private function _registerService($name,$class,$shared=false){  
        $this->remove($name);  
        if(!($class instanceof \Closure) && is_object($class)){  
            $this->_instances[$name] = $class;  
        }else{  
            $this->_bindings[$name] = array("class"=>$class,"shared"=>$shared);  
        }  
    }  
      
    //ArrayAccess接口,检测服务是否存在  
    public function offsetExists($offset) {  
        return $this->has($offset);  
    }  
      
    //ArrayAccess接口,以$di[$name]方式获取服务  
    public function offsetGet($offset) {  
        return $this->get($offset);  
    }  
      
    //ArrayAccess接口,以$di[$name]=$value方式注册服务，非共享  
    public function offsetSet($offset, $value) {  
        return $this->set($offset,$value);  
    }  
      
    //ArrayAccess接口,以unset($di[$name])方式卸载服务  
    public function offsetUnset($offset) {  
        return $this->remove($offset);  
    }  
}

<?php  
header("Content-Type:text/html;charset=utf8");  
class A{  
    public $name;  
    public $age;  
    public function __construct($name=""){  
        $this->name = $name;  
    }  
}  
  
include "Di.class.php";  
$di = new Di();  
//匿名函数方式注册一个名为a1的服务  
$di->setShared(&#39;a1&#39;,function($name=""){  
    return new A($name);  
});  
//直接以类名方式注册  
$di->set(&#39;a2&#39;,&#39;A&#39;);  
//直接传入实例化的对象  
$di->set(&#39;a3&#39;,new A("小唐"));  
  
$a1 = $di->get(&#39;a1&#39;,array("小李"));  
echo $a1->name."<br/>";//小李  
$a1_1 = $di->get(&#39;a1&#39;,array("小王"));  
echo $a1->name."<br/>";//小李  
echo $a1_1->name."<br/>";//小李  
  
$a2 = $di->get(&#39;a2&#39;,array("小张"));  
echo $a2->name."<br/>";//小张  
$a2_1 = $di->get(&#39;a2&#39;,array("小徐"));  
echo $a2->name."<br/>";//小张  
echo $a2_1->name."<br/>";//小徐  
  
$a3 = $di[&#39;a3&#39;];//可以直接通过数组方式获取服务对象  
echo $a3->name."<br/>";//小唐

unset($di['a1']);
or
$di->remove('a1');
判断是否包含一个服务可以通过
isset($di['a1']);
or
$di->has('a1');
就这么多了。