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From: jsa@alexandria (Jon S Anthony)
Subject: Re: Java vs Ada 95 (Was Re: Once again,
 Ada absent from DoD SBIR solicitation)
Date: 1996/10/16
Message-ID: <JSA.96Oct16173655@alexandria>#1/1
X-Deja-AN: 189922268
sender: news@organon.com (news)
references: <325BC3B3.41C6@hso.link.com>
 <Dz2B9H.9HD.0.-s@inmet.camb.inmet.com>
organization: Organon Motives, Inc.
newsgroups: comp.lang.ada
Date: 1996-10-16T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <Dz8znD.Fpt@thomsoft.com> kst@thomsoft.com (Keith Thompson) writes:

> In <JSA.96Oct11152501@alexandria> jsa@alexandria (Jon S Anthony) writes:
> [...]
> > But *languages* don't have GC.  Implementations of them do.  Even
> > Meyer says little about GC in ETL - just that all *implementations*
> > are *expected* to have it.
> 
> That's not *quite* correct.  It's admittedly difficult to define
> garbage collection in a formal language definition, but the Java
> definition at least attempts to do so.  Here's paragraph 20.16.9
> of The Java Language Specification, version 1.0 (available at
> <http://java.sun.com/doc/language_specification.html>).
> 
>         20.16.9 public void gc()
> 
>         Calling this method suggests that the Java Virtual Machine expend
>         effort toward recycling discarded objects in order to make the
>         memory they currently occupy available for quick reuse. When
>         control returns from the method call, the Java Virtual Machine
>         has made a best effort to recycle all discarded objects. (The
>         name gc stands for "garbage collector.")
> 
>         The Java runtime system will perform this recycling process
>         automatically as needed, in a separate thread, if the gc method
>         is not invoked explicitly.
> 
>         See also the method gc (�20.18.12) of class System, which is
>         the conventional and convenient means of invoking this method.
> 
> This does refer to the "Java Virtual Machine", but I don't think there's
> any requirement that the JVM be implemented via the usual byte code
> interpreter.

But the point is that it is talking about the JVM, _not_ JTL.  The JVM
is about a particular implementation.  Moreover, "suggests", "expend
effort toward", "made a best effort", etc. sounds a lot like "expected
to have".


> Even for a Java compiler that generates machine code directly, the
> runtime system has to provide a JVM implementation as specified in
> the language specification.  I think.

Where is this stated?  Even if true, I don't see the relevance.

/Jon



-- 
Jon Anthony
Organon Motives, Inc.
Belmont, MA 02178
617.484.3383
jsa@organon.com