* What's Pure for Dist Sytems? @ 1997-06-19 0:00 Dale Stanbrough 1997-06-19 0:00 ` Andre Spiegel 0 siblings, 1 reply; 7+ messages in thread From: Dale Stanbrough @ 1997-06-19 0:00 UTC (permalink / raw) After playing with Gnatdist and wanting to use it as a basis for some assignment work, I was struck by the extent of the restriction of only Pragma Pure for "Remote Call Interface" packages. I was especially upset at the restriction of no {un}bounded strings. Is there anything that i'm missing here? Dale ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-19 0:00 What's Pure for Dist Sytems? Dale Stanbrough @ 1997-06-19 0:00 ` Andre Spiegel 1997-06-19 0:00 ` Jon S Anthony 1997-06-20 0:00 ` Robert Dewar 0 siblings, 2 replies; 7+ messages in thread From: Andre Spiegel @ 1997-06-19 0:00 UTC (permalink / raw) Dale Stanbrough <dale@goanna.cs.rmit.EDU.AU> writes: > After playing with Gnatdist and wanting to use it as a basis for some > assignment work, I was struck by the extent of the restriction of only > Pragma Pure for "Remote Call Interface" packages. > I was especially upset at the restriction of no {un}bounded strings. > Is there anything that i'm missing here? There is a proposal to add pragma Remote_Types to some of the predefined packages (see Ada Issue ai-00126, at http://sw-eng.falls-church.va.us/AdaIC/standards/95com/ada-issues/). However, even under this proposal, Ada.Strings.Bounded and Ada.Strings.Unbounded are still non-remote. I find this an intolerable restriction, too, and I wonder if anyone sets out to remedy this... Andre Spiegel Free University of Berlin ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-19 0:00 ` Andre Spiegel @ 1997-06-19 0:00 ` Jon S Anthony 1997-06-20 0:00 ` Andre Spiegel 1997-06-20 0:00 ` Robert Dewar 1 sibling, 1 reply; 7+ messages in thread From: Jon S Anthony @ 1997-06-19 0:00 UTC (permalink / raw) In article <x2pvtianx1.fsf@inf.fu-berlin.de> Andre Spiegel <spiegel@inf.fu-berlin.de> writes: > > I was especially upset at the restriction of no {un}bounded strings. > > > Is there anything that i'm missing here? > > There is a proposal to add pragma Remote_Types to some of the > predefined packages (see Ada Issue ai-00126, at > http://sw-eng.falls-church.va.us/AdaIC/standards/95com/ada-issues/). > > However, even under this proposal, Ada.Strings.Bounded and > Ada.Strings.Unbounded are still non-remote. I find this an > intolerable restriction, too, and I wonder if anyone sets out to > remedy this... Use CORBA? The Ada=>IDL mapping fully supports this sort of thing. /Jon -- Jon Anthony OMI, Belmont, MA 02178 617.484.3383 "Nightmares - Ha! The way my life's been going lately, Who'd notice?" -- Londo Mollari ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-19 0:00 ` Jon S Anthony @ 1997-06-20 0:00 ` Andre Spiegel 1997-06-20 0:00 ` Jon S Anthony 0 siblings, 1 reply; 7+ messages in thread From: Andre Spiegel @ 1997-06-20 0:00 UTC (permalink / raw) jsa@alexandria.organon.com (Jon S Anthony) writes: > Andre Spiegel <spiegel@inf.fu-berlin.de> writes: > > However, even under this proposal, Ada.Strings.Bounded and > > Ada.Strings.Unbounded are still non-remote. I find this an > > intolerable restriction, too, and I wonder if anyone sets out to > > remedy this... > Use CORBA? The Ada=>IDL mapping fully supports this sort of thing. The nice thing about the Distributed Systems Annex is that it allows to distribute existing applications that were developed without distribution in mind. With CORBA it's usually different: you have to start by writing IDL for (at least) those objects that you want to distribute, and in your Ada code, you have to adhere to a programming style that is dictated by CORBA. I would rather use Ada only, and not care about distribution issues until very late in the development process. But you said "Ada=>IDL mapping"? Do you mean there's a reverse mapping that allows CORBA to be used for distributing existing Ada applications? That might be a different story. Andre Spiegel Free University of Berlin ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-20 0:00 ` Andre Spiegel @ 1997-06-20 0:00 ` Jon S Anthony 0 siblings, 0 replies; 7+ messages in thread From: Jon S Anthony @ 1997-06-20 0:00 UTC (permalink / raw) In article <x2bu51302t.fsf@inf.fu-berlin.de> Andre Spiegel <spiegel@inf.fu-berlin.de> writes: > jsa@alexandria.organon.com (Jon S Anthony) writes: > > > Use CORBA? The Ada=>IDL mapping fully supports this sort of thing. > > The nice thing about the Distributed Systems Annex is that it allows > to distribute existing applications that were developed without > distribution in mind. With CORBA it's usually different: you have to > start by writing IDL for (at least) those objects that you want to > distribute, and in your Ada code, you have to adhere to a programming > style that is dictated by CORBA. I don't think it forces that much. I mean it is pretty simple to put a CORBA wrapper around an existing set of capabilities. But you do have to write the IDL for the interface(s)... > I would rather use Ada only, and not care about distribution issues > until very late in the development process. Check. > But you said "Ada=>IDL mapping"? Do you mean there's a reverse > mapping that allows CORBA to be used for distributing existing Ada > applications? That might be a different story. No, I just fumbled the order... There was talk at one point for doing the Ada => IDL direction but nothing has come of it. Yet. /Jon -- Jon Anthony OMI, Belmont, MA 02178 617.484.3383 "Nightmares - Ha! The way my life's been going lately, Who'd notice?" -- Londo Mollari ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-19 0:00 ` Andre Spiegel 1997-06-19 0:00 ` Jon S Anthony @ 1997-06-20 0:00 ` Robert Dewar 1997-06-24 0:00 ` Andre Spiegel 1 sibling, 1 reply; 7+ messages in thread From: Robert Dewar @ 1997-06-20 0:00 UTC (permalink / raw) Andre says <<However, even under this proposal, Ada.Strings.Bounded and Ada.Strings.Unbounded are still non-remote. I find this an intolerable restriction, too, and I wonder if anyone sets out to remedy this...>> Finding something intolerable does not constitute a solution. I assume you understand *why* this rule is there. What is your proposal to "remedy this". ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: What's Pure for Dist Sytems? 1997-06-20 0:00 ` Robert Dewar @ 1997-06-24 0:00 ` Andre Spiegel 0 siblings, 0 replies; 7+ messages in thread From: Andre Spiegel @ 1997-06-24 0:00 UTC (permalink / raw) Robert Dewar writes: > Andre says > > <<However, even under this proposal, Ada.Strings.Bounded and > Ada.Strings.Unbounded are still non-remote. I find this an > intolerable restriction, too, and I wonder if anyone sets out to > remedy this...>> > Finding something intolerable does not constitute a solution. I assume you > understand *why* this rule is there. What is your proposal to "remedy this". As a matter of fact, I don't fully understand why these packages cannot be Remote_Types. This is how far I can follow the reasoning (please correct me if I'm wrong on any of this) - Ada.Strings.Unbounded cannot be remote, because (a) it depends on Ada.Strings.Maps, which cannot be pure because it declares an access-to-subprogram type (Character_Mapping_Function). But I don't see why this package cannot be Remote_Types. (b) Ada.Strings.Unbounded declares type String_Access, which is however not needed in the rest of the spec, and I recall that some people wondered if this type should be removed from the visible part of the specification. (c) if these two problems weren't there, one only would have to make sure that the package privately defines Read and Write attributes for Unbounded_String -- something that the GNAT version of the package already seems to do, judging from what I saw last time I looked. - Ada.Strings.Bounded cannot be remote, because it depends on Ada.Strings.Maps -- same reason as above. I don't see any other obstacles for Ada.Strings.Bounded. But what is the problem with Character_Mapping_Function anyway? If the string packages were Remote_Types, and Ada.Strings.Maps wasn't, how could a Character_Mapping_Function be used remotely then -- except by withing Ada.Strings.Maps _directly_ in the spec of a Remote_Call_Interface? RM95 E.2.2(6) says that a Remote_Types unit may only depend semantically on declared pure, remote types, or shared passive units. As far as I understand, this rule ensures that no remote variable reference, remote rendezvous, or unwanted remote access to anything is possible in a program. However, the predefined string packages use Ada.Strings.Maps only in such a way that no problems could arise from this, even if Ada.Strings.Maps had something in it that couldn't be made remote. So maybe the package categorization rules forbid more than they would have to? Could this be helped by different, possibly more complex rules that only forbid things that really cause problems? Andre Spiegel Free University of Berlin ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~1997-06-24 0:00 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 1997-06-19 0:00 What's Pure for Dist Sytems? Dale Stanbrough 1997-06-19 0:00 ` Andre Spiegel 1997-06-19 0:00 ` Jon S Anthony 1997-06-20 0:00 ` Andre Spiegel 1997-06-20 0:00 ` Jon S Anthony 1997-06-20 0:00 ` Robert Dewar 1997-06-24 0:00 ` Andre Spiegel
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