We all know that two heads are better than one. Apparently a head without a body can be more useful than one with a broken body.
This train of thought was prompted by an interesting question on the PL/SQL Challenge earlier this week (October 6, 2011 - to be precise). The question posed the puzzle about what happens when you reference a constant defined in the specification of a PL/SQL package if there was an invalid body.
My initial thought was that it is quite valid to have a package specification without a body, and you can safely references types and constants in that specification. I incorrectly assumed that an invalid body wouldn't be a problem.
One reason why it fails is that a body can contain an initialisation section. That is you can have:
CREATE OR REPLACE PACKAGE plch_pkg
g_stuff VARCHAR2 (10) := 'Stuff';
CREATE OR REPLACE PACKAGE BODY plch_pkg
dbms_output.put_line('Start it up');
This would output both "Start it up" and "Stuff". But of course it can only do that if the body is valid and can be executed by Oracle, which is why Oracle has to try to recompile an invalid package body and must throw an error if it fails.