Re: some questions re. Ada/GNAT from a C++/GCC user

[dewar@cs.nyu.edu (Robert Dewar)]

Bill asked:

The Ada Programming FAQ pooh-poohs STL, but I like it.  (Yes, I know I
could write my own versions of what I need, but a bunch of Ada
programmers shouldn't need to be told that that's not the ideal
solution.)  This FAQ also says the Booch components library is coming

  Those opinions do not represent the opinions of all in the Ada community
  by any means. The STL is a remarkable piece of work in my opinion. There
  is some very nice work going on at Rensaleer rewriting STL in Ada.

Does GNAT completely implement generics as defined in the standard?

  Yes

I *assume* that GNAT supports exceptions completely

  You assume correctly

I didn't notice anything about garbage collection in the GNAT docs, so
I assume it doesn't support it.  Will GNAT support GC in the
foreseeable future?

  We have no such plans. Several volunteers have mentioned projects to
  this effect. Perhaps you would like to help in this area!

How well does GDB work with GNAT output?

  Very well. We have used GDB for years to debug GNAT itself, and many
  of our customers have used it to debug large programs. There are
  areas where improvements are possible and planned, particularly
  in the tasking area.

  You assume correctly

I didn't notice anything about garbage collection in the GNAT docs, so
I assume it doesn't support it.  Will GNAT support GC in the
foreseeable future?

  We have no such plans. Several volunteers have mentioned projects to
  this effect. Perhaps you would like to help in this area!

How well does GDB work with GNAT output?

  Very well. We have used GDB for years to debug GNAT itself, and many
  of our customers have used it to debug large programs. There are
  areas where improvements are possible and planned, particularly
  in the tasking area.

Is it possible to get GDB to
interactively call arbitrary procedures/functions from GNAT-generated
code?

  Yes.

When I make two different instantiations of a generic package with the
same arguments, I understand the compiler treats them formally as two
different packages, which is OK with me.  However, I'd appreciate
knowing the compiler wouldn't actually output two redundant copies of
the corresponding (identical?) machine code, but instead share the
code.

  It is not easy in general to share code. GNAT always generates separate
  code which results in optimizing time at the expense of space.
  There are no plans to change this. (Note of course that plans can
  always be changed by customers with requirements and $$$$)

Can someone give me an idea what kind of compilation speed I could
expect from GNAT on a 486DX2/66 with 20 Mb of RAM, for projects of
1,000-50,000 lines?

  Why not just try it? the cost of a trial copy of GNAT is not expensive!
  Generally we see compilation speeds of several thousand lines a minute
  on such machines, but there are many variables.

Robert Dewar
Ada Core Technologies