create an object with variable CLASS

[Mohsen Pahlevanzadeh <mohsen@xxxxxxxxxxxxxxxxx>]

Dear all,
We know that we can create an object with following code:
/////////////////////////////////////////////////
class_name *object_name = new() class_name;
///////////////////////////////////////////////
So, i have a class pool,I wanna create Object with a variable name that
variable is my class.Same:
var *obj = new() var;
var is a variable that contains a my class's name.
How can i implement it?

Yours,
Mohsen