很奇怪，php 引入了phar，但是报错，说Predis\Client类找不到？

Question

<?php

require 'Predis.phar';
use Predis\Client;

ini_set('session.save_path', 'tcp://localhost:6379');
ini_set('session.name', 'YMFSESSION');
ini_set('session.save_handler', 'user');

class MySession implements SessionHandlerInterface {
    private $redis;

    private function connect() {
        if(!$this->redis) {
            $cfg = [
                'scheme' => 'tcp',
                'host' => '127.0.0.1',
                'port' =>  6379
            ];
            $this->redis = new \Predis\Client($cfg);
        }
    }

    /**
     * Close the session
     * @since 5.4.0
     */
    public function close()
    {
        $this->redis->quit();
        return true;
    }

    /**
     * Destroy a session
     * @since 5.4.0
     */
    public function destroy($session_id)
    {
        $this->connect();
        return $this->redis->del($session_id);
    }

    /**
     * Cleanup old sessions
     * @since 5.4.0
     */
    public function gc($maxlifetime)
    {
        return true;
    }

    /**
     * Initialize session
     * @since 5.4.0
     */
    public function open($save_path, $session_id)
    {
        return true;
    }

    /**
     * Read session data
     * @since 5.4.0
     */
    public function read($session_id)
    {
        $this->connect();
        $data = $this->redis->get($session_id);
        return $data;
    }

    /**
     * Write session data
     * @since 5.4.0
     */
    public function write($session_id, $session_data)
    {
        $this->connect();
        $expire  =  configure('Ymf.Account.expire');
        if(is_int($expire) && $expire > 0) {
            $result = $this->redis->setex($session_id, $expire, $session_data);
            $re = $result ? 'true' : 'false';
        }else{
            $result = $this->redis->set($session_id, $session_data);
            $re = $result ? 'true' : 'false';
        }
        var_dump($result);
        return $re;
    }
}


session_set_save_handler(new MySession());

session_start();

$_SESSION['name'] = 43;

这是目录

Answer 1

use 是使用命名空间的意思

use Predis\Client;

使用Predis空间下的 client 类

Answer 2

use \Predis\Client;

或者即然下面使用时用的完整命名空间，直接把use去掉