Re: Announce: Grace project site operational

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

Darren New <dnew@san.rr.com> writes:

> Well, it does just seem to me pretty trivial to write a program that
> takes something like
> 
> =distance
> =time
> velocity=distance/time
> area=distance*distance
> volume=distance*distance*distance
> 
> and turn such a file into the appropriate set of Ada type and function
> declarations, whether it's 50 lines or 5000 lines, that when "with"ed
> and "used" could make for safe unit conversions. 

I agree, it could be done. Please do it! 

> You need another unit? Add it to the file and regenerate the Ada. I
> mean, basically, isn't this what the C++ compiler is doing with the
> templates, 

Yes.

> except only creating those combinations you use?

I think this is critical. In a complex system, the Ada code you
generate will be huge, and could have an impact on compilation time.
GNAT's 'pragma Elaborate' and 'gnatelim' could be used to trim the
Units package after the system is built. It would be useful to do the
experiment and find out if this is worth it.

However, my personal belief is that units should be checked at
algorithm design time, which I prefer to do in Macsyma or Mathematica
for any moderately complex system. So I don't need the Ada code to
also check the units.

I guess if I had the 'Auto_Unit_Package', I might skip the Macsyma
step for more programs. Hmm.

> Of course, it could be made much more sophisticated too.

In what way?

> Or don't Ada people do things like that? :-)

Well, I have done something sort of like that, with Auto_Text_IO
(http://users.erols.com/leakstan/Stephe/Ada/auto_text_io.html). This
package automatically generates Text_IO Put and Get for record and
array types; something that is tedious to do by hand, but useful for
unit testing, and therefore a good candidate for automation.

Also, I believe parts of the GNAT compiler are tool-generated.

-- 
-- Stephe