Clarified Question - Mailing list pgsql-sql

Hello,Earlier I sent in some ramblings trying to explain my problm.
I think I have it better summarised now.

How can I create a function that will take in two variables and return
an integer, when one of the variables is the tablename ?!

I have tried :    create function tst_func(text, varchar(16))    as     'BEGIN        result=select max(history_id)+1
from$1            where client_id = $2;         return result;     END;'    
 
Please excuse the roughness of the code, I am not at my work machine
where I have postgres all setup. 

(oh. and jst a little query, is the 'max' actaully a stored procedureor an SQL keyword ?! I cant seem to find it in any
ofthe documentationprobbly cause I overlooked it ;)
 

Thanks,
Steffs