* Indentation @ 2014-08-08 16:12 Victor Porton 2014-08-08 16:32 ` Indentation Adam Beneschan 2014-08-08 16:38 ` Indentation Pascal Obry 0 siblings, 2 replies; 7+ messages in thread From: Victor Porton @ 2014-08-08 16:12 UTC (permalink / raw) What should be the indentation in the following Ada code fragment (especially its last line)? type T is record X: Integer; end record with Convention => C; -- Victor Porton - http://portonvictor.org ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 16:12 Indentation Victor Porton @ 2014-08-08 16:32 ` Adam Beneschan 2014-08-08 17:16 ` Indentation Jeffrey Carter 2014-08-08 16:38 ` Indentation Pascal Obry 1 sibling, 1 reply; 7+ messages in thread From: Adam Beneschan @ 2014-08-08 16:32 UTC (permalink / raw) On Friday, August 8, 2014 9:12:55 AM UTC-7, Victor Porton wrote: > What should be the indentation in the following Ada code fragment > > (especially its last line)? > > > > type T is > record > X: Integer; > end record > with Convention => C; An RM example in B.3.3 looks like: type T (Flag : Boolean := False) is record case Flag is when False => F1 : Float := 0.0; when True => F2 : Integer := 0; end case; end record with Unchecked_Union; That's as good an answer as you're going to get. Other people may have other preferences, but you really can't make an objective case for one or another style as long as it's reasonable. -- Adam ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 16:32 ` Indentation Adam Beneschan @ 2014-08-08 17:16 ` Jeffrey Carter 2014-08-08 17:45 ` Indentation Peter Chapin 2014-08-08 22:51 ` Indentation Randy Brukardt 0 siblings, 2 replies; 7+ messages in thread From: Jeffrey Carter @ 2014-08-08 17:16 UTC (permalink / raw) On 08/08/2014 09:32 AM, Adam Beneschan wrote: > > An RM example in B.3.3 looks like: > > type T (Flag : Boolean := False) is > record > case Flag is > when False => > F1 : Float := 0.0; > when True => > F2 : Integer := 0; > end case; > end record > with Unchecked_Union; > > That's as good an answer as you're going to get. Other people may have other preferences, but you really can't make an objective case for one or another style as long as it's reasonable. That depends on whether people can agree on a precise specification of why indentation is used. The compiler doesn't care, so it must be for humans, and as it increases writing complexity, it must be for readers. So if we have a precise statement of what indentation is supposed to convey to readers we can speak more objectively about it than just "this is what I like" or "this is what the ARM uses". For me, indentation exists to reflect nesting. If A is indented 1 indentation level from B, then A is nested directly within B; if A is indented 2 levels, then it is nested directly in something else (C) that is nested directly within B. With this definition, the indentation in the ARM example is clearly incorrect. The case statement is nested directly within the type declaration, but is indented 2 levels; F1 and F2 are nested directly within the case statement but are indented another 2 levels. What is new in Ada 12 that I haven't worked with yet is the aspect clause. This is clearly part of the type declaration, not nested within it, and so should be part of the type framing text. So I would probably indent this as type T (Flag : Boolean := False) is record case Flag is when False => F1 : Float := 0.0; when True => F2 : Integer := 0; end case; end record with Unchecked_Union; For a lengthy aspect clause, I like something that indicates clearly that the declaration is not finished yet, so I'd probably use end record with <aspect 1>, <aspect 2>, ..., <aspect N>; I've never heard a reason for indentation that resulted in the indentation used by the ARM, or a satisfactory explanation of why the ARM indents record type declarations and case statements the way it does. If one should write type T is record then surely one should also write type T is range type T is array and the like. At the Ada launch (1980 Dec 10), Ichbiah talked about "comb structures" driving the layout of code, and the ARM indentation of records and cases seems to violate that rule. Of course, the ARM indentation goes back to Ada 80, and one can argue that the ARM is never wrong, in which case indentation is arbitrary and the only rule can be "use what the ARM uses". -- Jeff Carter "We call your door-opening request a silly thing." Monty Python & the Holy Grail 17 ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 17:16 ` Indentation Jeffrey Carter @ 2014-08-08 17:45 ` Peter Chapin 2014-08-08 17:50 ` Indentation Peter Chapin 2014-08-08 22:51 ` Indentation Randy Brukardt 1 sibling, 1 reply; 7+ messages in thread From: Peter Chapin @ 2014-08-08 17:45 UTC (permalink / raw) On 2014-08-08 13:16, Jeffrey Carter wrote: > What is new in Ada 12 that I haven't worked with yet is the aspect > clause. This is clearly part of the type declaration, not nested within > it, and so should be part of the type framing text. So I would probably > indent this as > > type T (Flag : Boolean := False) is record > case Flag is > when False => > F1 : Float := 0.0; > when True => > F2 : Integer := 0; > end case; > end record with Unchecked_Union; To my mind the aspects should be introduced on a separate line so they aren't lost. I had to review the declaration above a couple of times before I realized the aspect was even there. I favor indenting the aspect. Consider the common case where there are multiple declarations at the same level type X_Type is ...; type Y_Type is ...; procedure A(...); function B(...) return ...; If you slip an aspect in at the same level of indentation as the declaration to which it is attached it clutters things considerably. type X_Type is ... with ...; type Y_Type is ... with ...; procedure A(...) with ...; function B(...) return ... with ...; Of course adding some blank likes would help but I still like to see the aspect set off so its association with the previous declaration is obvious type X_Type is... with ...; type Y_Type is ... with ...; procedure A(...) with ...; function B(...) return ... with ...; Peter ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 17:45 ` Indentation Peter Chapin @ 2014-08-08 17:50 ` Peter Chapin 0 siblings, 0 replies; 7+ messages in thread From: Peter Chapin @ 2014-08-08 17:50 UTC (permalink / raw) On 2014-08-08 13:45, Peter Chapin wrote: > I favor indenting the aspect. Consider the common case where there are > multiple declarations at the same level... I forgot to mention (sorry) that if the aspect's value is complex, such as often the case for Pre, Post, and other assertions, it is normal for the aspect itself to span multiple lines. Trying to put it on the same line as the declaration is crazy in that case and not indenting it doesn't work well either. Then, for consistency it seems natural to treat all aspects the same way. -- Division returns quotient and remainder. procedure Divide (Dividend : in Very_Long; Divisor : in Very_Long; Quotient : out Very_Long; Remainder : out Very_Long) with Depends => (Quotient => (Dividend, Divisor, Quotient), Remainder => (Dividend, Divisor, Remainder)), Pre => (not Is_Zero(Divisor)) and (Divisor.Digit_Length = Remainder.Digit_Length) and (Dividend.Digit_Length = Quotient.Digit_Length ) and (Dividend.Digit_Length = 2*Divisor.Digit_Length); Peter ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 17:16 ` Indentation Jeffrey Carter 2014-08-08 17:45 ` Indentation Peter Chapin @ 2014-08-08 22:51 ` Randy Brukardt 1 sibling, 0 replies; 7+ messages in thread From: Randy Brukardt @ 2014-08-08 22:51 UTC (permalink / raw) "Jeffrey Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message news:ls30lf$cj2$2@dont-email.me... ... > Of course, the ARM indentation goes back to Ada 80, and one can argue that > the ARM is never wrong, in which case indentation is arbitrary and the > only rule can be "use what the ARM uses". My understanding is that the Ada 9x team went through the entire standard and regularized the indentation. (It's not really from Ada 80 anymore.) Remember, they also switched to Title case identifiers (Ada 83 had them all in UPPER CASE - yuck!). Since, we pretty much take it as given. For aspects, we had a long and rather inconclusive discussion about how they ought to be indented. The style shown in the RM is what we settled on, but it wasn't close to unanimous. The only indentation that I know I do differently than the RM is record types (I think the RM inserts an extra level there for no reason). Otherwise, I follow the RM style pretty closely (more closely as the years go by). Randy. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Indentation 2014-08-08 16:12 Indentation Victor Porton 2014-08-08 16:32 ` Indentation Adam Beneschan @ 2014-08-08 16:38 ` Pascal Obry 1 sibling, 0 replies; 7+ messages in thread From: Pascal Obry @ 2014-08-08 16:38 UTC (permalink / raw) Le vendredi 08 août 2014 à 19:12 +0300, Victor Porton a écrit : > What should be the indentation in the following Ada code fragment > (especially its last line)? > > type T is > record > X: Integer; > end record > with Convention => C; For me: type T is record X: Integer; end record with Convention => C; 3 lines. If there is multiple aspects, probably: type T is record X: Integer; end record with Pass_By_Copy => True, Convention => C; or type T is record X: Integer; end record with Pass_By_Copy => True, Convention => C; Not sure yet as this is quite recent and I did not use such aspects. -- Pascal Obry / Magny Les Hameaux (78) The best way to travel is by means of imagination http://v2p.fr.eu.org http://www.obry.net gpg --keyserver keys.gnupg.net --recv-key F949BD3B ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-08-08 22:51 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-08-08 16:12 Indentation Victor Porton 2014-08-08 16:32 ` Indentation Adam Beneschan 2014-08-08 17:16 ` Indentation Jeffrey Carter 2014-08-08 17:45 ` Indentation Peter Chapin 2014-08-08 17:50 ` Indentation Peter Chapin 2014-08-08 22:51 ` Indentation Randy Brukardt 2014-08-08 16:38 ` Indentation Pascal Obry
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