Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!apple!cremer
From: cremer@Apple.COM (Mike Cremer)
Newsgroups: comp.sys.mac.programmer
Subject: Re: MPW 3.0 Pascal Unit Header Format
Keywords: MPW 3.0,Pascal,PIncludes,Header
Message-ID: <2418@internal.Apple.COM>
Date: 20 Jun 89 02:47:34 GMT
References: <4017@hacgate.scg.hac.com> <1431@laura.UUCP>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 31

In article <4017@hacgate.scg.hac.com> djnowak@luna.dpl.scg.hac.com (David Nowak)
 writes:
>    Every Unit definition in the PIncludes folder of MPW 3.0 has a header
>format of the following type:
>{$IFC UNDEFINED UsingIncludes}
>{$SETC UsingIncludes := 0}
>{$ENDC}
........
>where XXXXXX corresponds to the name of the unit file.  I am curious to know
>what do these compiler directives do?

MPW 3.0 header files have been broken out to match the structure of
_Inside Macintosh_.  However, several of the files depend on definitions
in other files.  Most headers require the same base definitions
(like "{PInterfaces}Types.p") and it would be pointless and time-consuming
to read "Types.p" every time a new header file was parsed.  The compiler
directives allow MPW Pascal to intelligently determine which header files
need to be included and which have already been parsed.

Hope this helps.

$mike cremer

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