如何为Scope Resolution Operator提供常规变量

Question

$version = \jamesiarmes\PhpEws\Client::$ews_version;

抛出

  

未捕获错误：访问未声明的静态属性：

其中$ews_version是客户提供的变量，其可能值为：

$ews_version = 'VERSION_2007';
$ews_version = 'VERSION_2007_SP1';
$ews_version = 'VERSION_2009';
$ews_version = 'VERSION_2010';
$ews_version = 'VERSION_2010_SP1';
$ews_version = 'VERSION_2010_SP2';
$ews_version = 'VERSION_2013';
$ews_version = 'VERSION_2013_SP1';
$ews_version = 'VERSION_2016';

手动提供const，工作正常：

$version = \jamesiarmes\PhpEws\Client::VERSION_2013_SP1;

请帮忙。谢谢。

代码：

$ews_version = $_REQUEST['version']; // User posted version (i.e. VERSION_2009)

// Set connection information.
$host = $ews_host;
$username = $ews_username;
$password = $ews_password;
$version = \jamesiarmes\PhpEws\Client::$ews_version;

$client = new \jamesiarmes\PhpEws\Client($host, $username, $password, $version);

Answer 1

我认为您正在尝试使用变量访问常量。

您可以使用反射解决此问题：

$ews_version = 'VERSION_2007';
$ref = new ReflectionClass(\jamesiarmes\PhpEws\Client::class);
$version = $ref->getConstant($ews_version);