Status: Proposal ERROR accepted 12/91
References: ASSERT (Condition System, Revision #18, p27)
Edit history: 15-Mar-91, Version 1 by Pitman
The condition system proposal says that ASSERT signals SIMPLE-ERROR
if the datum is omitted. This unnecessarily restricts an
Define that if the datum is omitted, ASSERT signals ERROR.
(HANDLER-CASE (HANDLER-CASE (ASSERT NIL) (SIMPLE-ERROR 1)) (ERROR 2))
Under Conditions System revision #18, this must return 1.
Under proposal ASSERT-ERROR-TYPE:ERROR, this might return either 1 or 2.
This leaves an implementation free to experiment with error types
specific to assertions. Since the user is free to specify whatever
type he needs, he can always work around any implementation-specific
type in any way he wants.
In Symbolics Genera 8.1, the test case returns 1.
Cost to Implementors:
None. (Since SIMPLE-ERROR is a subtype of ERROR, no change is forced.
This just adds flexibility to implementations which want to do this
Cost to Users:
Little or none. There are probably very few people who are
specifically doing HANDLER-CASE for SIMPLE-ERROR with the intent
of specifically catching ASSERT.
Cost of Non-Adoption:
Implementations have their hands tied unnecessarily.
Aesthetics. Implementation flexibility.
Makes language more consistent in that this was the only place where
SIMPLE-ERROR was forced in a situation where the user wasn't supplying
a format string.
This issue was raised by Barrett several meetings ago, but was never
formally written up.
Pitman supports this.