php function how to set default value as object?

Question

A function (actually the constructor of another class) needs an object of class temp as argument. So I define interface itemp and include itemp $obj as the function argument. This is fine, and I must pass class temp objects to my function. But now I want to set default value to this itemp $obj argument. How can I accomplish this?

Or is it not possible?

The test code to clarify:

interface itemp { public function get(); }  class temp implements itemp {     private $_var;     public function __construct($var = NULL) { $this->_var = $var; }     public function get() { return $this->_var ; } } $defaultTempObj = new temp('Default');  function func1(itemp $obj) {     print "Got: " . $obj->get() . " as argument.\n"; }  function func2(itemp $obj = $defaultTempObj) //error : unexpected T_VARIABLE {     print "Got: " . $obj->get() . " as argument.\n"; }  $tempObj = new temp('foo');  func1($defaultTempObj); // Got: Default as argument. func1($tempObj); // Got : foo as argument. func1(); // "error : argument 1 must implement interface itemp (should print Default)" //func2(); // Could not test as I can't define it 

Answer 1

You can't. But you can easily do that:

function func2(itemp $obj = null)     if ($obj === null) {         $obj = new temp('Default');     }     // .... }