PERFORM function in Plpgsql

hello,

i want to call a function (function1() for example )in an other function.
simple,i guess :

....
PERFORM function1() ;
.....

it's ok, but the name of my function is a variable like :


.....
var_function := function1();
.....
PERFORM var_function;


and it doesn't work !!!
Is it possible to do that ?

thanks


version :
 PostgreSQL 7.3.4 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.3.1
(Mandrake Linux 9.2 3.3.1-1mdk)