for S'Image use Func??
in [ADA]
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From: Keith Thompson on 7 May 2010 14:24 "Randy Brukardt" <randy(a)rrsoftware.com> writes: > "Adam Beneschan" <adam(a)irvine.com> wrote in message > news:2318cabb-080c-42a0-8219-21c347abe172(a)o11g2000yqj.googlegroups.com... > On May 6, 10:10 am, Warren <ve3...(a)gmail.com> wrote: > ... >>Broadly, you can't use a FOR attribute specification on every >>attribute, just a few select ones that the language specifically says >>you can. 'Image isn't one of those. >> >>I think it's been mentioned a few times on this newsgroup that it >>might be nice to have this ability, but I don't see that anyone has >>submitted an actual language change proposal. > > I believe we looked at it semi-seriously back during the Ada 2005, but we > ran into some problems (I don't recall the details - might have been > visibility) and decided it wasn't worth the headache. > > It would probably be possible with some work. The interaction with 'Value and 'Width, and with the Wide_ and Wide_Wide_ variants of all three attributes, would be ... interesting. -- Keith Thompson (The_Other_Keith) kst-u(a)mib.org <http://www.ghoti.net/~kst> Nokia "We must do something. This is something. Therefore, we must do this." -- Antony Jay and Jonathan Lynn, "Yes Minister"
From: Simon Wright on 7 May 2010 15:29 Stephen Leake <stephen_leake(a)stephe-leake.org> writes: > "Dmitry A. Kazakov" <mailbox(a)dmitry-kazakov.de> writes: >> So, T'Image has some minor advantages. (The argument would really work >> if it were V'Image or V.Image) > > It's Foo.Bar.T'Image vs Foo.Bar.Images.Image. No problem. I know it's an implementation-defined attribute, but for non-operational quick-and-dirty code that doesn't need to be portable I use GNAT's V'Img (shame it still has the leading space for positive numbers!) Sometimes the 'Image way is useful even in that sort of context: Duration'Image (Finish_Time - Start_Time) avoids the need for a local variable which 'Img would require.
From: J-P. Rosen on 7 May 2010 15:56 Robert A Duff a �crit : > "J-P. Rosen" <rosen(a)adalog.fr> writes: > >> Robert A Duff a �crit : >>> But for "columns" you want something like: >>> >>> 1 >>> -3 >>> 123 >>> -123 >>> >>> But 'Image gives you: >>> >>> 1 >>> -3 >>> 123 >>> -123 >>> >>> I don't get it. 'Image isn't particularly helpful in producing >>> columnar output. >> >> 'Image is just for quick, debug-like output. > > So that's why it's broken?! I was just responding that 'Image is not for columns, and of course I agree that the extra space was a mistake - just like making Priority a subtype of Integer. -- --------------------------------------------------------- J-P. Rosen (rosen(a)adalog.fr) Visit Adalog's web site at http://www.adalog.fr
From: Robert A Duff on 7 May 2010 16:10 Simon Wright <simon(a)pushface.org> writes: > Sometimes the 'Image way is useful even in that sort of context: > Duration'Image (Finish_Time - Start_Time) > avoids the need for a local variable which 'Img would require. By the way, I think this: Put_Line (Duration'(Finish_Time - Start_Time)'Img); will be legal in Ada 2012. Well, the 'Img is still a GNAT-specific thing, but I'm talking about the ability to use a qualified expression as the prefix of an attribute. Now why isn't this: Put_Line ((Finish_Time - Start_Time)'Img); legal? I don't know, but the language is moving in that direction -- maybe by 2099, the syntactic distinction between expression and name (and the semantic distinction between value and object) will disappear entirely. - Bob
From: Robert A Duff on 7 May 2010 16:14
"J-P. Rosen" <rosen(a)adalog.fr> writes: > Robert A Duff a �crit : >> So that's why it's broken?! > I was just responding that 'Image is not for columns, and of course I > agree that the extra space was a mistake Oh, OK, then we agree. That was my point, too: 'Image is not for columns, so "for columns" can't explain the extra blank. >... - just like making Priority a > subtype of Integer. I agree, but students won't run into that one in the first week of the beginner's class. First impressions matter. - Bob |