Re: Garbage collection?

[news.byu.edu!news.mtholyoke.edu!nic.umass.edu!nic.umass.edu!hudson@gatech .edu (Rick Hudson)]

>>>>> On 21 Apr 92 21:09:54 GMT, mcroberts@titan.ksc.nasa.gov said:

mcroberts> I've been looking at two different Ada textbooks which have
mcroberts> very different ideas about garbage collection.  The older
mcroberts> book says that a good Ada compiler should take care of it for
mcroberts> you and you should avoid unchecked_deallocation.  The newer
mcroberts> one says that you need to manage storage yourself using
mcroberts> unchecked_deallocation. I'm curious as to the state of the
mcroberts> art in automated garbage collection.  

The older book is correct. The language was designed to allow GC.
Unfortunately, the newer book reflects the (1992) reality of the situation.
Ada does have the advantage over C++ in that accurate (non-conservative)
collectors can be implemented for the language.  See our upcoming Sigplan
paper (referenced below) for a discussion of how to implement an accurate GC
for languages like Ada along with some of the costs.

@Unpublished{DMH91,
  author = 	 "Amer Diwan and J. Eliot B. Moss and Richard L. Hudson",
  title = 	 "Compiler Support for Garbage Collection in a Statically
  Typed Language",
  note = 	 "To appear in SIGPLAN PLDI",
  OPTcrossref =  "",
  OPTkey = 	 "",
  year = 	 1992,
  OPTmonth = 	 "",
  OPTannote = 	 ""
}
--

                Richard L. Hudson, Research Associate
                University Computing Services
                Lederle Graduate Research Center
                University of Massachusetts
                Amherst, MA  01003
                (413) 545-1220; Hudson@cs.umass.edu