On Jun 27, 2011, at 19:26 , Steve Haflich wrote:

...

Marco Antoniotti wrote:

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Now, this is a specific case for me: having a consistent READER-ERROR-BECAUSE-THERE-IS-NO-SUCH-PACKAGE-THAT-THE-SYSTEM-KNOWS error signaled would simplify some code writing.

I agree with the sentiment, what is the specific proposal may need more work.

Of course... this is jut one example. There may be other cases, plus unexplored ones: FILE-ERROR is rather underspecified, so are PARSE-ERROR and PROGRAM-ERROR. I'd like to see a discussion started....

Would you want this same condition to be signaled for this form?

(defpackage :foo (:use :not-yet-loaded))

That's an error, but not a reader error the way reading not-yet-loaded:bar would be. Still, it would be nice if these shared a common superclass because what the application might want to do to handle would be the same.

These would both be PACKAGE-ERRORs, but different

Unfortunately, the condition system does not portably support multiple inheritance.

Yes, I'll grant you that and see where you are going. This is another CDR: The Condition system should use the CLOS algorithm to determine/use/offer multiple inheritance derived properties.

Cheers

-- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://bimib.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY

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