Re: C/C++ knocks the crap out of Ada

[Ed Falis <falis@east.thomsoft.com>]

Jon S Anthony wrote:
> 
> In article <4iupk7$5t4@tpd.dsccc.com> kcline@sun132.spd.dsccc.com (Kevin Cline) writes:
> 
> > BTW, what architectures does ObjectAda support, and will ObjectAda
> > code compile largely unmodified with Gnat, and vice versa?
> 
> A Thompson guy could better answer this.  I would be surprised
> if Gnat and ObjectAda didn't compile things with little or no
> modification.  Heck, I've taken large chuncks of VAX Ada and moved
> them to Gnat with no changes.  Of course, these did not have any
> OS specific stuff in them.
> 

Well, I'll give it a shot.  This year, it'll be Wintel, PowerPC/Win NT, 
Sun/Solaris, HP-UX and (I believe) PowerPC/AIX.  We also expect Wintel 
cross to 32 bit X86 this year.  Various PowerPC and 68K cross early next 
year.

My experience so far is that the ability to cross compile code developed 
on GNAT or ObjectAda is pretty good - the main issues are in a couple of 
areas: one or other of the front-ends is a bit stronger in "corners" of 
the language, availability of identical bindings, and application use of 
implementation defined pragmas (Unchecked_Union definitely comes to 
mind, per discussion on another thread).  On the other hand, there are 
an awful lot of issues that we used to see with Ada 83 compilers that 
just aren't there any more, especially such things as vendor defined 
unsigned types, low-level operations on addresses, shift operations etc. 
 And these latter issues have always been the real ugly ones I've seen - 
where client code is calling 
"vendor_x_system.ought_to_have_been_defined_in_the_standard;"

and it has to be reorganized or changed in hundreds of places.  
Obviously this was poor design, but Ada 95 will still help with its more 
uniform treatment of these kinds of issues.

- Ed
Ed Falis	
Thomson Software   falis@thomsoft.com	(617) 221-7341
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Ideological disarmament: a koan for the 21st century
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