Ada (was: D (was: Quo vadis,

[J. David Bryan]

On Saturday, July 31, 2010 at 6:01, Frank Heckenbach wrote:

> For the 3 big things I mentioned, I know C++ has them already. I don't
> know if Ada does, perhaps you can give us some information here, e.g.,
> is its object model comparable to those GPC supports or that of C++;

I am not familiar with objects in GPC, and only tangentially familiar with 
C++ (i.e., have not done any serious programming in it).  However, the 
short answer is yes; objects are called "tagged types" in Ada.

There is a guide that discusses comparable Ada and C++ features here:

  http://www.adahome.com/Ammo/Cplpl2Ada.html

or more nicely formatted here:

  http://home.agh.edu.pl/~jpi/download/ada/guide-c2ada.pdf

It has a section devoted to the Ada object model:

  http://www.adahome.com/Ammo/Cplpl2Ada.html#3

(Note that this guide discusses Ada 95, which superceded the original Ada 
83, and has itself been superceded by Ada 2005.  As such, it is a bit out 
of date, although language revisions have been kept backward-compatible.  
Ada undergoes periodic improvements; the next language revision is 
scheduled for 2012.)


> does Ada supported exception handling and how; 

Yes; see:

  http://www.adahome.com/Ammo/Cplpl2Ada.html#1.2.7


> does it support something like templates (IOW, how can one implement,
> say, a generic list, applicable to any given type, with strong
> type-checking). 

Yes; templates are called "generics" in Ada.  See:

  http://www.adahome.com/Ammo/Cplpl2Ada.html#4


> Packed arrays/records and array slices can be implemented in C++ code
> with moderate effort....

Indeed, any language may be used as the intermediate for GPC.  However, I 
would expect that the effort required to write a translator would vary, 
depending on the closeness of the mapping between GPC and that language.  
My impression is that C++ doesn't map particularly well to Pascal's type 
structure (subranges, sets, packed structures), and while that may be 
overcome with moderate effort, as you say, that effort may be less with a 
different choice of intermediate language.  Granted, though, that this 
mapping is just one of several variables influencing that choice.


> I fear this might only be true for more traditional Pascal, while I
> stated that I'm particularly interested in more "modern" features
> that I know from C++. Of course, if Ada also supports them, it would
> make it more interesting.

"Modern" features, such as templates and exception handling, have been 
present in Ada from the beginning (1983).  :-)

                                      -- Dave