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From: mishkin@apollo.uucp (Nathaniel Mishkin)
Newsgroups: comp.sys.apollo
Subject: Re: Apollo Pascal and Modules
Message-ID: <3869b66d.c366@apollo.uucp>
Date: Wed, 11-Nov-87 09:33:00 EST
Article-I.D.: apollo.3869b66d.c366
Posted: Wed Nov 11 09:33:00 1987
Date-Received: Fri, 13-Nov-87 22:00:57 EST
References: <678@zycad.UUCP>
Reply-To: mishkin@apollo.UUCP (Nathaniel Mishkin)
Organization: Apollo Computer, Chelmsford, MA
Lines: 35

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