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From: Stephen Leake <Stephe.Leake@nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Boehm-Demers-Weiser conservative garbage collector and GNAT
Date: 23 Jun 2003 17:11:18 -0400
Organization: NASA Goddard Space Flight Center (skates.gsfc.nasa.gov)
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Date: 2003-06-23T21:11:43+00:00
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Florian Weimer <fw@deneb.enyo.de> writes:

> Stephen Leake <Stephe.Leake@nasa.gov> writes:
> 
> > I wrote a container library that does all the memory management I
> > need.
> 
> How do you prevent client code from keeping references to objects in
> the container at the point of its finalization?  

My library does allow this. It is not a bullet-proof, "assume the
client is an idiot" library.

See the discussion on Grace lists for some reasons why.

however, I normally code my apps so the container is always active;
it's created when the app starts, and is one of the last things
finalized when the app is shutting down.

> Is erroneous execution a possibility?

Yes, in the sense that Ada + my library allows it.

> I don't think memory leaks are the most severe problem, dangling
> references are.

Yes. 

However, note that I said "all the memory management I need", not "all
the memory protection a novice needs". Some small amount of discipline
is expected on the part of the client; the goal is to get a good
balance between container efficiency and protection against bugs.

Now someone will say "C struck a better balance"; more power to them
:).

The issue of whether garbage collection is a good thing for novice
programmers is an interesting one. My initial take would still be "no
- don't let them get used to the crutch". But I'm willing to be
convinced.

-- 
-- Stephe