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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Warning: Flame Bait
Date: 1996/11/30
Message-ID: <E1o04r.D0F@world.std.com>#1/1
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references: <01bbdcb5$7500ab30$24af1486@pc-phw> <E1nLxo.Ly3@world.std.com>
 <dewar.849319316@merv>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-11-30T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.849319316@merv>, Robert Dewar <dewar@merv.cs.nyu.edu> wrote:
>Portability is MUCH more than just a question of the language definition, it
>is about being able to practically port a wide range of applications from
>one machine to another over a wide range of machines. Java does not yet
>begin to meet either of these criteria. We have to wait to see whether
>it can in the future, but right now, Java is quite limited in its reasonable
>application domain in practice, and I don't see too many Java compilers for
>the 1750A, let alone the 8051 :-)

Quite true.  Portability in practice is quite different from portability
in theory.  Java has the "theory" part done quite nicely -- a Java
program that works properly on one machine will work the same on any
other machine that correctly supports the Java language (except for
issues involving shared variable updates by multiple threads).  You
can't say that about Ada, since Ada doesn't define lots of things (order
of evaluation of arguments, pass-by-reference vs. pass-by-value,
semantics of arithmetic overflow, etc -- I could name several tens of
cases).  On the other hand, if a Java compiler doesn't exist on your
machine, you're out of luck.  Likewise, if your machine doesn't have a
word size that is a power of 2, Java can't be compiled efficiently for
it.  The designers of Java clearly valued portability above all else,
including efficiency, and there are many situations where Java simply is
inappropriate.

We'll see what happens.  Java may well be the final nail in the coffin
for weird machines.  Hmm.

Anyway, it's hard to reason about portability "in practice".  Think
about all the C programmers who write code assuming sizeof(int) =
sizeof(char*), and write code that is quite portable -- in practice.  My
taste wants some more basis, than, "I ported it to 3 machines, and it
seemed to work."  I have this itchy feeling -- I want to *know* that it
will port.

- Bob