From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,45a9122ddf5fcf5 X-Google-Attributes: gid103376,public From: "Norman H. Cohen" Subject: Re: Valid Attribute and Unchecked Conversion Date: 1996/10/11 Message-ID: <325E70C5.1DB8@watson.ibm.com>#1/1 X-Deja-AN: 188755862 references: content-type: text/plain; charset=us-ascii organization: IBM Thomas J. Watson Research Center mime-version: 1.0 reply-to: ncohen@watson.ibm.com newsgroups: comp.lang.ada x-mailer: Mozilla 3.0 (Win95; I) Date: 1996-10-11T00:00:00+00:00 List-Id: Concerning sparse enumeration types, Robert Dewar wrote: > Furthermore, we found that > we had to add the additional complexity of makeing sure that arrays indexed > by such types were compact (rather than mapped sparsely), since a couple of > large customers required this support. But the work necessary to do this (mapping sparse encodings to a contiguous set of values that can be used for array indexing) is already necessary anyway to implement the 'Pos attribute. The Ada-83 RM contained a note (RM83-13.3(6)) warning that operations such as 'Succ, 'Pred, 'Pos, and array indexing are likely to be less efficient for sparse enumeration types than for ordinary ones. The warning is gone from the corresponding note in the Ada-95 RM (RM95-14.4(11)), but surely the expectation of slower operations is still there. -- Norman H. Cohen mailto:ncohen@watson.ibm.com http://www.research.ibm.com/people/n/ncohen