How to provide regular variable to Scope Resolution Operator

Question

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

Throws

Uncaught Error: Access to undeclared static property:

Where $ews_version is a client provided variable with possible values of:

$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';

Providing const manually, works fine:

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

Please help. Thanks.

Code:

$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

I think you are trying to access a constant using a variable.

You can solve this using reflection:

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