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 !