<I>Problem Description:
~~~~~~~~~~~~~~~~~~~~
All roles are disabled in any *named* PL/SQL block that
     * is created in a user schema that does not own the object being
        referenced in the PL/SQL block
     * can be executed as a user other than the owner of the PL/SQL block
This applies to stored procedures and functions, as well as database triggers.

You can also see this by selecting from the data 
dictionary view called SESSION_ROLES.

This view shows all roles that are currently enabled.  If you query SESSION_ROLES from a stored object, 
the query will not return any rows.
This is not true in Oracle8i when the stored object is created with 
AUTHID  CURRENT_USER.

Roles vs. GRANTs and REVOKEs:
-----------------------------
Do not confuse roles with GRANTs and REVOKEs 
-- Roles are meant to be toggled on and off on a per session basis, 
whereas GRANTs and REVOKEs (as well as any associated dependencies) 
updates the data dictionary because they are DDL   operations.
This is why it becomes an issue of gross ambiguity:  A user can potentially 
log on in the form of two sessions, one with the role enabled, the 
other one with the role disabled, and the outcome of both sessions will not be the same.

Hence, the restriction that stored object creation cannot depend on privileges 
granted through a role is added in the Oracle7 to avoid ambiguous cases of this nature. 
Notice that anonymous PL/SQL blocks are not bound to this restriction, 
therefore they are executed based on privileges granted through enabled roles. </I>