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Lazy error signaling?
- To: Jon L White <firstname.lastname@example.org>
- Subject: Lazy error signaling?
- From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Tue, 8 May 90 10:33 EDT
- Cc: Common-Lisp-Object-System@MCC.COM
- In-reply-to: <9005080334.AA05154@ptl-club>
Date: Mon, 7 May 90 20:34:40 PDT
From: Jon L White <email@example.com>
88-002R, page 1-30 says:
"In standard method combination, if there is an applicable method
bug no applicable primary method, an error is signaled."
Some have interpreted that to mean that it is OK to define an :around
method that doesn't call CALL-NEXT-METHOD, since the error signaling
in this case should only be triggered when an attempt is made to call
the non-existent primary method. Others take the stricter view that
the error should be signaled at effective-method computation time,
regardless of whether or not CALL-NEXT-METHOD is involved.
All this part of 88-002R takes no stand on exactly when these errors are
signalled. The way I remember the CLOS design discussions, the intent
was that the program was erroneous if there was no applicable primary
method, regardless of whether the flow of control would actually try to
reach that primary method or not. This is what you call the stricter view.
In Genera 8.0.1, compute-effective-method signals the error.