kjb@zycad.UUCP (Kevin Buchs) (11/07/87)
I have been working on modifying some old Apollo Pascal code
and in adding new features I have been trying to make it
more modular. By this I mean the use of seperate source
code files and the "Module" declaration. Under this
implementation, there is a "main" module, which is the one
headed with Program, instead of Module. One may call any
procedure/function defined in any non-main module from any
module including the main module. There is one thing I
don't understand: Why can one not make calls to
procedures/functions in the "main" module from one of the
non-main modules?
I am using the trivial workaround now of having a 1 line
main module which calls a routine in a non-main module.
In other words, I took all the code out of the main module
and put in into a non-main module, where I can call it
from any other non-main module.
Are there other more clever workarounds, perhaps involving
the use of extern qualifiers?
--
Kevin Buchs 3500 Zycad Dr. Oakdale, MN 55109 (612)779-5548
Zycad Corp. {rutgers,ihnp4,amdahl,umn-cs}!meccts!nis!zycad!kjbErstad@HI-MULTICS.ARPA (11/10/87)
You certainly can call main module procedures from any module. However, as with any Pascal code tehe procedures you want to call must be declared. The declaration is similar to a FORWARD declaration, except that since the procedures called are outside the non-main compilation unit an EXTERN declaration is used instead You are probably already doing this to declare your non-main procedures to your main program (If not, you should) The above should work, although I've never had the occasion to call a main program procedure from a module. I'm not even sure I can think of a good situation where I would want to do that... Dave Erstad, Honeywell SSED
mishkin@apollo.uucp (Nathaniel Mishkin) (11/11/87)
In article <678@zycad.UUCP> kjb@zycad.UUCP (Kevin Buchs) writes: >One may call any >procedure/function defined in any non-main module from any >module including the main module. There is one thing I >don't understand: Why can one not make calls to >procedures/functions in the "main" module from one of the >non-main modules? I can't claim to being a Pascal purist who understands the "deep" reasons for this sort of behavior, but I think the jist of the answer is this: Apollo extends Pascal by allowing multiple modules and supporting "global" ("external") and "non-global" ("internal") procedures. Procedures declared in "program"s are implicitly (and un-overridably) treated as "internal". I suspect this is because this is a "natural" extension of standard Pascal where all procedures could be thought of as being "internal". >I am using the trivial workaround now of having a 1 line >main module which calls a routine in a non-main module. >In other words, I took all the code out of the main module >and put in into a non-main module, where I can call it >from any other non-main module. > >Are there other more clever workarounds, perhaps involving >the use of extern qualifiers? Another technique is to have no "program" but instead have all "module"s, put the stuff that would have been in the "program"'s "begin/end" block into a procedure called (say) "main", and use the binder's "-entry" option: bind -b myprogram mymod1.bin mymod2.bin -entry main -- -- Nat Mishkin Apollo Computer Inc. Chelmsford, MA {decvax,mit-eddie,umix}!apollo!mishkin
Erstad@HI-MULTICS.ARPA.UUCP (11/12/87)
My earlier approach to making main module procedures available to non-main modules was incorrect. Isent it off before testing. I tried it out, and it doesn't work - DOMAIN Pascal does not consider the main module procedures to be global symbols. Sorry about any confusion.
trb@stag.UUCP ( Todd Burkey ) (11/15/87)
In article <678@zycad.UUCP> kjb@zycad.UUCP (Kevin Buchs) writes: > Why can one not make calls to >procedures/functions in the "main" module from one of the >non-main modules? Yep, I wasted a morning trying to get this to work too...(it wasn't too explicit in the Apollo manuals that I couldn't do it). It may seem like a trivial problem, but it causes other messy coding 'workarounds' that are likely to haunt you if you every get into an environment like we have (>1 million lines of code of Apollo Pascal scattered around on 200+ nodes in DSEE). Makes C (or even ADA) look so nice at times. -Todd Burkey trb@stag.UUCP