Constructors not called when using classmap option in SoapClient

When using classmap option to map the SOAP results to a class, the constructor
of the object you've mapped to is not called. 

$client = new SoapClient("url_to_wsdl", 
   array('classmap' => array('contact' => "Contact"));

$params = array("1");

$contact = $client->__soapCall("get_contact", $params);

Expected result:

A contact object that has properties initialized (i.e. db connections,
....).

Actual result:

A contact object without the properties.


Thanks for your help.

David Georges.