Filter multidimensional arrays using unset and array_filter

class A{
	/**
	 *  多维数组过滤包含指定元素的子数组
	 *	 $menu_list				菜单（一个四维数组）
	 *  $mmenu 					接收过滤后的菜单
	 *  $member_limits  	保存在表中的菜单字段
	 */
	public function Multi_dimensional_array (){
		//    
		$menu_list = $this->_getMemberMenuList();
		$mmenu = array();
		$member_limits = $this->member_limits();
		// 用&对原始数据进行写操作
		foreach($menu_list as  &$value){
			foreach($value['child'] as $k => $v){
				if(!in_array($k,$member_limits)){
					//清除元素
					unset($value['child'][$k]);
				}
			}	
		}
		// array($this,"_Filter") 相当于 $this->_Filter()
		$mmenu = array_filter($menu_list, array($this,"_Filter"));
	}
	
	/**
	 *  array_filter 数组回调函数
	 *  将判断为空的指定元素过滤掉
	 */
	protected function _Filter($value){
		foreach($value['child'] as $k => $v){
			$result = isset($value['child']);
			if($result){
				return $result ;
			}
		}
	}
}