problem with a global variable as class reference

i am using a global variable (curClass), which is a reference to some class, inside another class i want to change the value of this global variable, to "point" or refer to another class. but that doesnt work. am i doing something wrong??? here my code ------------------ class temp {   function temp()   {     global $curClass;     $curClass = &${$classNameY};   } } ------------- $curClass = &${classNameX}; $tempi = new temp(); # at this point $curClass still points # to the class with the name "classNameX" # not to "classNameY" as i would suppose # if i used: $curClass = $classNameY; # inside the class temp # $curClass would have the expected value # but with the "&${}" around it doenst work thanks 4 your help Wolfram Kriesing