Subject:
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Re: Something else is needed, I think...
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 4 May 1999 08:47:30 GMT
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Viewed:
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1036 times
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In lugnet.robotics, Kekoa Proudfoot writes:
> John A. Tamplin <jat@liveonthenet.com> wrote:
> > The things I like about using JVM (in no particular order):
> > ===========================================================
> > 1) huge variety of development tools and expertise on many platforms
> > 2) compact bytecode
> > 3) full-featured support for objects, threading and exceptions
> > 4) compiler and interpreter do strict static error checking, interpreter
> > does strict dynamic error checking
> > 5) JVM is all the interface required to the OS (ie, in C you have libraries
> > to do threading, you can have direct access to the hardware, etc)
> > 6) portability (specifically it would be easy to write RCX emulation • classes
> > and run that on any JVM). If it is designed right, the same user code
> > should run on any future upgrade of the RCX.
> >
> > Things I dislike
> > ================
> > 1) relying on garbage collection on a memory-constrained device
> > 2) licensing issues requiring that it implement the full JVM spec
>
> So this is a nice start at least.
>
> Regarding things you like, I'm going to ignore 1) and 6) because they are
> not features of byte code, they are features of Java; you either use the
> JVM and you get them, or you do not use the JVM and you do not get them.
> There's not much more to say about them than that.
Yes but in regard to 1) we do not have to implement a compiler, they arer
already there, all we need is the VM.
>
> Regarding 2), this is a given, everybody wants the byte code to be
> compact. Can you shed any light into how Java is made compact? Is it
> something non-obvious and different from the standard byte code, and if so,
> how is it different?
>
> Regarding 3), these are nice features. With regards to threading, how does
> the JVM support this feature? How is it exposed in the byte code? I am
> particularly interested what the JVM thinks is the state associated with a
> single thread (e.g. a stack, a PC, etc.).
There is a stack and a PC.
>
> Regarding 4), this is a nice goal. I think it's straightforward in
> principle to understand.
>
> Regarding 5), I agree with hiding all OS/hardware issues in the virtual
> machine. The JVM does this, the standard byte code does this, and I think
> everybody will agree that any new byte code should do this.
No way, OS/hardware specific stuff should be in the RCX specific systemclasses,
they will offcourse contain a mix of bytecode and native calls.
The VM needs a native interface for this.
>
> You dislikes are noted.
>
> -Kekoa
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Message is in Reply To:
 | | Re: Something else is needed, I think...
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| (...) So this is a nice start at least. Regarding things you like, I'm going to ignore 1) and 6) because they are not features of byte code, they are features of Java; you either use the JVM and you get them, or you do not use the JVM and you do not (...) (25 years ago, 3-May-99, to lugnet.robotics)
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