1:所谓链式操作最简单的理解就是 操作完毕之后再返回对象$this
例如:
- $model->where()->field()->limit()->select()
2:代码实现
<?php
namespace IMooc;
class Database
{
static private $db;
private function __construct()
{
}
static function getInstance()
{
if (empty(self::$db)) {
self::$db = new self;
return self::$db;
} else {
return self::$db;
}
}
function where($where)
{
return $this;
}
function order($order)
{
return $this;
}
function limit($limit)
{
return $this;
}
function query($sql)
{
echo "SQL: $sql\n";
}
}
$obj = new Database();
//链式操作
$obj->where()->limit()->order()->query();
就是这么esay!!!