NICE-ESG-Libs Digest Tue, 27 Feb 96 Volume 2 : Issue 22
Today's Topics:
NICE-ESG-Libs Digest V2 #21
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Date: Tue, 27 Feb 1996 10:01:15 -0500
From: jcm@mstr.hgc.edu
Subject: NICE-ESG-Libs Digest V2 #21
To: NICE-ESG-Libs@atlanta.twr.com
> From root@atlanta.twr.com Mon Feb 26 22:32:43 1996
> Reply-To: NICE-ESG-Libs@atlanta.twr.com
> Subject: NICE-ESG-Libs Digest V2 #21
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> NICE-ESG-Libs Digest Mon, 26 Feb 96 Volume 2 : Issue 21
>
> Today's Topics:
> Class ARRAY proposal
>
> ----------------------------------------------------------------------
> NICE Eiffel Standards Group -- Library Committee Mailing List
>
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> Date: Mon, 26 Feb 1996 18:10:25 -0800 (PST)
> >From: ericb@eiffel.com (Eric Bezault)
> Subject: Class ARRAY proposal
> To: NICE-ESG-Libs@atlanta.twr.com (NICE ESG LIBS)
>
> Dear Library Committee members,
>
> As the new delegate for ISE to the NICE Library Committee,
> I reviewed once again Jim McKim's proposal for class ARRAY
> and noticed some minor problems. Here they are:
>
> o The precondition of feature `size' says:
>
> valid_indices: min_index <= max_index
>
> which prevents us from "sizing" to an empty array. Since it is allowed
> to create an empty array, I suggest that it should also be possible
> to size it to empty as well. So I propose the following precondition
> in replacement to the former one:
>
> valid_indices: min_index <= max_index + 1
>
> Note that it is the same as in `make'.
I agree that this change is fully appropriate.
[..]
>
> o The following precondition
>
> type_identity: same_type (other)
>
> from GENERAL is missing in `copy'. Jim told me that it was not intentional.
> So I propose this precondition to be added to feature `copy'.
This omission was indeed unintentional, but reflects a broader problem.
There are many places in ELKS where only the immediate assertions are
shown, as opposed to the full flat-short form. I'd recommend that the
Committee try to clean these up as part of producing a Vintage '96. I'd
also recommend that with Vintage '95, you assume any omissions of ancestor
assertions be treated as errors. That is, you assume that it was _not_
the intent to somehow remove the ancestor's assertions.
>
> o In the RB-3 amendment (and also in the original proposal and Bertrand's
> suggestion), one can read as one of the postconditions of `is_equal':
>
> definition: -- Result = (lower = other.lower) and (upper = other.upper)
> and for_all i, lower..upper (item (i) = other.item (i))
>
> However the check for item equality is not valid when the bounds are not
> the same. In my view, that postcondition should be:
>
> definition: -- Result = (lower = other.lower) and (upper = other.upper)
> and then for_all i, lower..upper (item (i) = other.item (i))
>
> Note the "and then" instead of "and" before "for_all".
I agree. Even though it's "just a comment" it ought to be stated as carefully
as if it _could_ be compiled.
[...]
>
>
> Best regards,
>
>
> --
> Eric Bezault
> Interactive Software Engineering Inc.
> 270 Storke Road, Suite #7 / Tel +1 (805) 685-1006 \
> Goleta, California 93117, USA \ Fax +1 (805) 685-6869 /
>
> ==================================================
>
> End of NICE-ESG-Libs Digest
> ******************************
>
Thanks Eric,
-- Jim
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