Ripple effect
in [ADA]
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From: Jeffrey R. Carter on 23 Aug 2006 18:29 On the Ada-Comment mailing list recently, Robert Duff shared some ideas on language design for a language he is thinking about (which may be called Nada, but is definitely not called Duff). In this language, there is no equivalent of the Ada "use" and primitive operators ("+", "-") of a type are directly visible wherever the type is used. I recall that during the Ada-9X revision process, it was proposed that primitive operators of a type have this kind of visibility. IIRC, one of the reasons that this was not accepted was that it would lead to Ripple effects: adding or removing a unit from a context clause could change one legal program to a different legal program. If Herr Doktor Professor Duff is interested, I'd like to hear his thoughts on the matter, and how Nada (or whatever) deals with this. -- Jeff Carter "Brave Sir Robin ran away." Monty Python and the Holy Grail 59
From: Maciej Sobczak on 24 Aug 2006 05:21 Jeffrey R. Carter wrote: > I recall that during the Ada-9X revision process, it was proposed that > primitive operators of a type have this kind of visibility. IIRC, one of > the reasons that this was not accepted was that it would lead to Ripple > effects: adding or removing a unit from a context clause could change > one legal program to a different legal program. Why? If you remove some use clause that might affect the visibility of some primitive operation, then it will also remove the whole type that is involved in a given expression, rendering the whole as illegal. Could you provide a short example of this Ripple effect? -- Maciej Sobczak : http://www.msobczak.com/ Programming : http://www.msobczak.com/prog/
From: Adam Beneschan on 24 Aug 2006 14:22 Jeffrey R. Carter wrote: > I recall that during the Ada-9X revision process, it was proposed that > primitive operators of a type have this kind of visibility. IIRC, one of > the reasons that this was not accepted was that it would lead to Ripple > effects: adding or removing a unit from a context clause could change > one legal program to a different legal program. This has nothing to do with the topic. But my understanding is that the Beaujolais effect was named because Jean Ichbiah offered a bottle of Beaujolais wine to anyone who could find a certain anomaly in the language. So are you saying that if someone finds a Ripple effect, you're going to offer them a bottle of .... ??? Aaahh... I don't even think they sell it any more. -- Adam
From: Jeffrey R. Carter on 24 Aug 2006 19:39 Maciej Sobczak wrote: > > Why? > If you remove some use clause that might affect the visibility of some > primitive operation, then it will also remove the whole type that is > involved in a given expression, rendering the whole as illegal. > > Could you provide a short example of this Ripple effect? No. I'm simply aware that STT cites direct operator visibility as potentially giving rise to the Ripple effect in the Ada FAQ http://www.adapower.com/index.php?Command=Class&ClassID=FAQ&CID=358 -- Jeff Carter "Now go away or I shall taunt you a second time." Monty Python & the Holy Grail 07
From: Jeffrey R. Carter on 24 Aug 2006 19:40
Adam Beneschan wrote: > > This has nothing to do with the topic. But my understanding is that > the Beaujolais effect was named because Jean Ichbiah offered a bottle > of Beaujolais wine to anyone who could find a certain anomaly in the > language. So are you saying that if someone finds a Ripple effect, > you're going to offer them a bottle of .... ??? What topic? I started this thread about the Ripple effect and direct operator visibility. It has little to do with the Beaujolais effect. Information about the Ripple effect is available at http://www.adapower.com/index.php?Command=Class&ClassID=FAQ&CID=358 -- Jeff Carter "Now go away or I shall taunt you a second time." Monty Python & the Holy Grail 07 |