Re: Garbage Collection in Ada

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

Jonas said

Recently there has been some topics that has touched on the issue
of Garbage Collection, GC, in Ada. I peronally think it would be great to
have GC in Ada and I am not sure why there is such resistance.
I have a couple of questions on this GC issue.

  I don't think anyone resists the idea that it would be attractive for
  Ada implementations to implement GC, although there always in the past
  has been opposition to the idea of requiring this feature. However,
  there does not seem to be any great commercial interest. No one seems
  interested enough so far to consider funding such a capability, and
  so far no Ada company has estimated that there is sufficient interest
  to warrant investing their own resources in such an implementation
  effort. Perhaps, as I have noted before, Java will change the landscape
  enough to change this state of affairs.

Many claim GC is not well suited for real-time applications - well if it is
possible at all to implement GC in Ada then it is just a question of making
the GC feature optional. This could be accomplished by compile-time
'switches' to turn GC on or off. Or one could use the same strategy as
for Ada.Finalization, e.g.:

  Obviously pragma Restrictions is the appropriate way to handle such
  a capability!

Probably the greatest obstacle is to implement GC. I have tried to study
some of the papers available and at times I believe I understand the
different approaches available but I soon lose clarity when I try to
understand how one would go about to implement it. My understanding of
compiler technology and internals is way low.

  That's the only obstacle. Obviously if it were easy to implement optional
  garbage collection, everyone would do it!

So my second question: Is it at all possible to implement GC in Ada ?
(with a reasonable effort, whatever that is),

  Yes, abosolutely it is possible. I am sure that any Ada company would be
  happy to give you a quotation on what it would take to implement this
  feature if you are seriously interested!