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From: Simon Wright on 10 Jun 2010 15:45 Georg Bauhaus <rm.dash-bauhaus(a)futureapps.de> writes: > with Ada.Text_IO; use Ada.Text_IO; > > procedure Sttc is > > type T is range 0 .. 10; > > procedure A is > package P is > V: T; pragma Export (C, V, "naughty_v"); --<<<<<<<<<< > end P; > begin > if P.V'Valid then > P.V := P.V + 1; > else > P.V := T'First; > end if; > Put_Line (T'Image(P.V)); > end A; > > procedure Ovrwrt_Stk is > X : T; > begin > X := T'First; > end Ovrwrt_Stk; > > begin > A; Ovrwrt_Stk; A; Ovrwrt_Stk; A; Ovrwrt_Stk; A; > end Sttc; > > $ ./sttc > 0 > 1 > 1 > 1 > $ > > Phew. Back to normal. $ gnatmake sttc -f -gnatVa gcc -c -gnatVa sttc.adb sttc.adb:10:28: warning: "V" has been made static as a result of Export sttc.adb:10:28: warning: this usage is non-standard and non-portable gnatbind -x sttc.ali gnatlink sttc.ali $ ./sttc 1 2 3 4 (this is a GNAT-ism, of course, and is present in at least GNAT Pro 3.16a1 for powerpc-wrs-vxworks and GCC 4.5.0 for x86_64-apple-darwin10).
From: Niklas Holsti on 10 Jun 2010 16:09 Simon Wright wrote: > Georg Bauhaus <rm.dash-bauhaus(a)futureapps.de> writes: > >> with Ada.Text_IO; use Ada.Text_IO; >> >> procedure Sttc is >> >> type T is range 0 .. 10; >> >> procedure A is >> package P is >> V: T; > pragma Export (C, V, "naughty_v"); --<<<<<<<<<< >> end P; >> begin >> if P.V'Valid then >> P.V := P.V + 1; >> else >> P.V := T'First; >> end if; >> Put_Line (T'Image(P.V)); >> end A; >> >> procedure Ovrwrt_Stk is >> X : T; >> begin >> X := T'First; >> end Ovrwrt_Stk; >> >> begin >> A; Ovrwrt_Stk; A; Ovrwrt_Stk; A; Ovrwrt_Stk; A; >> end Sttc; >> >> $ ./sttc >> 0 >> 1 >> 1 >> 1 >> $ >> >> Phew. Back to normal. > > $ gnatmake sttc -f -gnatVa > gcc -c -gnatVa sttc.adb > sttc.adb:10:28: warning: "V" has been made static as a result of Export > sttc.adb:10:28: warning: this usage is non-standard and non-portable > gnatbind -x sttc.ali > gnatlink sttc.ali > $ ./sttc > 1 > 2 > 3 > 4 > > (this is a GNAT-ism, of course, and is present in at least GNAT Pro > 3.16a1 for powerpc-wrs-vxworks and GCC 4.5.0 for x86_64-apple-darwin10). It is also present in GNAT 4.3 in debian lenny. You can even initialize V in its declaration, for example as V : T : = T'First, and GNAT will make this initialization happen once. No need for the unreliable trickery with 'Valid. Interesting curio to know, but as for using it... nah. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ .
From: Randy Brukardt on 10 Jun 2010 17:59 "AdaMagica" <christoph.grein(a)eurocopter.com> wrote in message news:4db36585-569d-4f24-ab95-0c7177e5d09b(a)d8g2000yqf.googlegroups.com... On 10 Jun., 08:13, "Randy Brukardt" <ra...(a)rrsoftware.com> wrote: >> When this is done, even the use of objects of 'Class can be managed with >> Ada.Containers, and any needed dynamic allocation can be completely >> hidden >> from the program. (And it rarely is needed in the first place.) > >Randy, which AI is the favoured solution (there are several >proposals)? The current Amendment 2 RM is still Draft 8 which does not >include this accessor magic. Right. AI05-0139-2 contains the syntax, AI05-0142-4 contains a related feature, and AI05-0212-1 contains the changes needed to the predefined containers for the first two. I'd wait to read those until next week; Tucker is supposed to be providing major updates to AI05-0139-2 and AI05-0142-4 by tomorrow afternoon and I'll be posting them over the weekend before leaving for Vallencia. (AI05-0212-1 is mostly empty still, waiting for the other two to get much closer to completion. We had problems deciding on names of things in the past (even though no one use those names, we still have to have them), but otherwise the basic structure is already known). Also in the next few days, the next AARM draft will be posted. Randy.
From: Randy Brukardt on 10 Jun 2010 18:08 "Vadim Godunko" <vgodunko(a)gmail.com> wrote in message news:35dd1a8f-1af8-4979-9663-29f7f4cb302e(a)g19g2000yqc.googlegroups.com... On Jun 10, 10:54 am, Yannick Duch�ne (Hibou57) <yannick_duch...(a)yahoo.fr> wrote: >> Le Thu, 10 Jun 2010 08:34:07 +0200, Vadim Godunko <vgodu...(a)gmail.com> a >> �crit:> I want to known more about how to use OOP in Ada without access >> types! >> >> Wadim, if saying OOP, you meant dynamic dispatching, then you are indeed >> not required to use access type for that. >No, I more asked for real example where Ada's OOP is be used without >access types in OOP way. The only known example is Tuker's work on >some part of ASIS 05, but from my point of view this work is set of >tricks and assumptions successful for concrete example but not for >general use. Claw only uses a handful of access types in its interfaces (internally is a different story, but irrelevant to this discussion). Most Claw example programs use no access types at all. > By "access types" I mean access to classwide types. If you need to do this, using an indefinite container to hold the objects is preferable to using explicit access types. Again, access types probably are used to implement the container, but they aren't visible anywhere. This eliminates the horrors of explicit storage management and most (or all, depending on the implementation) of the unsafeness of access types without any distributed overhead. (Unlike garbage collection, which has to be done on all objects to work, so even objects that don't need management have to pay for it.) Randy.
From: Randy Brukardt on 10 Jun 2010 18:17
"Georg Bauhaus" <rm.dash-bauhaus(a)futureapps.de> wrote in message news:4c10baa2$0$6974$9b4e6d93(a)newsspool4.arcor-online.net... > On 10.06.10 10:57, Vadim Godunko wrote: >> On Jun 10, 11:20 am, AdaMagica <christoph.gr...(a)eurocopter.com> wrote: >>> On 10 Jun., 08:34, Vadim Godunko <vgodu...(a)gmail.com> wrote: >>> >>>> I want to known more about how to use OOP in Ada without access types! >>> >>> type Element is tagged ... >>> subtype Any_Element is Element'Class; >>> >>> procedure Show (E: Element); >>> >> Thank you for example, this is example of dispatching but not use of >> Ada in heavy OOP style of programming. :-) > > Will it, in theory, be possible to write a Qt-like library > in Ada such that client programs declare variables like > > W : Some_Window'Class := Some_Lib_Pack.Make (Typ => Some_Id); > > That is, programs do not use access Some_Window'Class? We could have done this in Claw, but we found little need for "generic windows". At some point, you have to declare the specific window object that you need, and at that point you might as well just declare an object of that type. Claw allows window objects to be assigned, so you could definitely do something like: declare My_Window : Claw.Basic_Window.Window; begin Global_Window := Root_Window_Type'Class(My_Window); end; Unfortunately, Ada doesn't allow the changing of the tags of declared classwide objects. (This is a language bug in my view, but hardly anyone elses.) So you have to use an Ada 2012 holder container: declare My_Window : Claw.Basic_Window.Window; begin Global_Window.Replace_Element (Root_Window_Type'Class(My_Window)); end; where Global_Window is defined as: package Global_Holder is new Ada.Containers.Indefinite_Holder (Claw.Root_Window_Type'Class); Global_Window : Global_Holder; Randy. |