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=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail From: "Jeffrey R. Carter" Newsgroups: comp.lang.ada Subject: Re: class wide iterable (and indexable) Date: Sun, 6 Jan 2019 11:11:26 +0100 Organization: Also freenews.netfront.net; news.tornevall.net; news.eternal-september.org Message-ID: References: <2a6929c5-72fa-4d84-953a-44ea4597ab38@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sun, 6 Jan 2019 10:11:28 -0000 (UTC) Injection-Info: reader01.eternal-september.org; posting-host="fcd5e5c85f35845e1a584d50a40e7932"; logging-data="5271"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18ug6zdQk2cOLa/Dy9UYkcQHErhVW8NAiY=" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 Cancel-Lock: sha1:1ETAjR2pinPFW3FPAIizMtxLW6w= In-Reply-To: Content-Language: en-US Xref: reader01.eternal-september.org comp.lang.ada:55212 Date: 2019-01-06T11:11:26+01:00 List-Id: On 1/5/19 10:09 PM, Shark8 wrote: > > Hm, I'm not sure I agree with you -- plug-ins seem to be a counter-example in that they *are* extensions [of the base program] -- it seems a bit excessive to think that any program that uses/handles plug-ins is ill-designed and by-nature violative of good SW engineering. I don't think plug-ins qualify as programming by extension, since they don't involve extending an existing type (I'm not very familiar with how plug-ins are written for things that allow them, so I may be mistaken). But I'm not sure that allowing plug-ins is good S/W eng. The goals of S/W eng are S/W that is correct, reliable, robust, and easy to understand and modify. How do you ensure that if you allow any coder to write a plug-in? > Of course this is an interesting observation in its own right, and I should like to hear more. My observations about programming by extension are in the /Ada Letters/ articles "Ada's Design Goals and Object-Oriented Programming", "Breaking the Ada Privacy Act", and "OOP vs. Readability", available at http://pragmada.x10hosting.com/papers.html These are over 20 years old. The 1st and last deal with type extension and the 2nd with child pkgs that extend their ancestor(s). The type-extension examples I cite do not use child pkgs, perhaps because both were new concepts in Ada and the authors did not want to confuse readers with an extra new concept, but I don't think revising them to use child pkgs would change anything. -- Jeff Carter "Now look, Col. Batguano, if that really is your name." Dr. Strangelove 31