Re: Dave Emery's proposal for Ada preprocessor

[sdl@herbrand.Inference.Com (Daniel Lee)]

We are developing a commercial Ada-based tool (expert system tool in
particular) which has to run on multiple platforms possibly on
multiple compilers on the same hardware.  We found that the lack
of Ada tool similar to cpp makes it very hard to maintain portable Ada code
across multiple platforms, and yet Ada is designed for portability.

Currently, we are using cpp on a Sun to preprocess the master Ada
source with cpp macros embedded (e.g. #if, #endif, etc.).  Then, we preprocess
it using cpp.  First, we defined app as follows:

/lib/cpp $1 $2 $3 $4 $5 $6 $7 $8 $9 | grep -v "^#"

Then, we do the following:

app -DVERDIX foo.a.master > foo.a   or
app -DVMS foo.a.master > foo.ada

The problem with this is that foo.a.master is still not a compilable
Ada file and has to be preprocessed manually while its C equivalent
is a direct input to a C compiler.  I agree with Dave that if such
thing as cpp is added to Ada, it should be part of STANDARD Ada
so that only a single source file has to be maintained.

				Danile Lee
				Inference Corporation
				sdl@inference.com