Path: utzoo!attcan!uunet!husc6!mailrus!ames!vsi1!daver!athsys!jim
From: jim@athsys.uucp (Jim Becker)
Newsgroups: comp.lang.c++
Subject: Re: Including header files minimally.
Message-ID: <186@tityus.UUCP>
Date: 15 Nov 88 01:25:19 GMT
References: <3561@pt.cs.cmu.edu>
Organization: Athena Systems, Inc., Sunnyvale, CA
Lines: 47

From article <3561@pt.cs.cmu.edu>, by dld@f.gp.cs.cmu.edu (David Detlefs):
>
	[stuff deleted]
> 
> It would be nice if you could precompile each header file to get a
> symbol table (both preprocessor and language tables -- this scheme
> would require an integrated preprocessor/compiler) that you would dump
> to a file. [clipped]
> 

	Something fairly equivalent to this existed in the Amiga
world, and it's net effect was excellent. I found that using this type
of approach made development on a 68000/floppy based Amiga faster than
a 80286/harddisk system! This was part of the Manx development system
(aka - Aztec C).

	The implementation consisted of having a special option for
the compiler that would take the symbol table that it currently had
and outputing the content as a "library" file. Not a standard type
library, but a library of symbols that were known. This creation I did
using a C file that contained #include statements for all the standard
include files that I used in the system. They were then bundled into
this small binary format library.

	During subsequent compilation, the created symbol library file
was included in the command line. Any include files that were needed
from during the compilation process were semantically extracted from
the symbol library when they were needed. Include files that were not
in the symbol library were processed normally.

	The result was a DRAMATIC improvement in the compilation
speed! I have been surprised that this concept hasn't yet come into
other products that I have crossed paths with, as it seems very
elegant and nice (w/ not much effort).

	We just received the Oregon C++ compiler, I hope they may
integrate something such as this into their compiler to help further
improve the speed of compilation!!


> 
> -- 
> Dave Detlefs		
> Carnegie-Mellon CS	


-Jim Becker