using vars in ddl in procedure call

Hi:

v9.0.1 on linux.

Trying (failing) a test to see if I can run ddl in a procedure where elements of the ddl are vars. Consider...

create or replace function newcol (text) returns integer as $$
declare
newcol alias for $1;
begin

alter table target add column newcol text;

return(0);

end;
$$ language plpgsql;

This successfully adds a column called "newcol" instead of what I passed it as an arg.

Any suggestions on how to make this work?

Thanks !