PHP, COM objects, and out parameters

I'm using PHP to work with a COM object and one of the COM object's function's parameters is an "out" parameter. How does PHP work with these?

Example (ModifyParam could do 开发者_开发技巧anything, like output the word of the day or provide an object):

$MyCom = new COM("APPLib.APP");

$outParam;
//APP.ModifyParam(out object pParam)
$MyCom->ModifyParam($outParam);

var_dump($outParam); //NULL

The example is based on actual code which outputs what would be an object array, or an array of strings. The real code isn't outputting the list though.

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As far as I know (you can correct me if I'm wrong here) - the [out] parameter means the variable to store the results. So if you have this method in the COM object:

GetUserInfo([in] long machineID, [out] long* userID, [out] BSTR* userName)

The [in] parameter means the argument, the [out] parameter are result variables that will get written, much like how MySQLi::bind_result() method works. Example code to use the method above (assuming the COM object has been set appropriately):

$obj = new COM('Namespace.Class');

// This is the [in] parameter, the machine number we wanted to inspect.
$machineID = 1

// Define [out] variables with the correct type, according to the API.
$userID = 0;
$userName = '';

// Call the COM method.
$obj->GetUserInfo($machineID, $userID, $userName);

// Print the results.
echo "User ID: $userID<br />";
echo "User Name: $userName";