It's already possible to create class instance with :
1) a string:
   <?php
   class Foo {}
   $foo = new Foo;
   ?>
2) a variable:
   <?php
   class Foo {}
   $class = 'Foo';
   $foo = new $class;
   ?>
3) a variable variable:
   <?php
   class Foo {}
   $class = 'Foo';
   $name = 'class';
   $foo = new $$name;
   ?>
This commit add the possibility to use an expression :
   <?php
   class Foo {}
   $oo = 'oo';
   $foo = new {'f' . $oo};
   ?>