[Pharo-dev] Purpose of VM [was: Re: Better management of encoding of environment variables]

Eliot Miranda eliot.miranda at gmail.com
Thu Jan 17 13:40:15 EST 2019


On Thu, Jan 17, 2019 at 8:02 AM Sven Van Caekenberghe <sven at stfx.eu> wrote:

>
> > On 17 Jan 2019, at 02:00, Martin McClure <martin at hand2mouse.com> wrote:
> >
> > On 1/16/19 1:24 AM, Nicolas Cellier wrote:
> >> IMO, windows VM (and plugins) should do the UCS2 -> UTF8 conversion
> because the purpose of a VM is to provide an OS independant façade.
> >
> > I have not looked at this particular problem in detail, so I have no
> opinion on whether the VM is the right place for this particular
> functionality.
> >
> > However, I feel that in general trying to put everything that might be
> OS-specific into the VM is not the best design. To me, the purpose of a
> Smalltalk VM is to present an object-oriented abstraction of the underlying
> machine.
> >
> > Thinking that way leads me to believe that the following are examples of
> things that are good for a VM to do:
> >
> > * Memory is garbage-collected objects, not bytes.
> >
> > * Instructions are bytecodes, not underlying machine instructions.
> >
> > This works well to hide the differences between machine instruction
> sets, memory access, and other low-level things. However, no Smalltalk
> implementation that I know of has been able to use the VM to iron out all
> differences between different OSes.
> >
> > I do believe that it is a good idea to have cleanly-designed layers of
> the system, and that there should be an OS-independent layer and an
> OS-dependent layer with clean separation. But I think it might be better to
> put most of the OS-dependent layer in the image rather than in the VM. For
> one thing, the image is easier to change if there is a bug, or a lacking
> feature, or you're trying to support a new OS.
> >
> > And if it's in the image you get to do the programming in Smalltalk
> rather than C or Slang, which is more fun for most of us. And, let's face
> it, fun is an important metric in an open-source project -- things that are
> fun are much more likely to get done.
>
> +100
>

The VM *is* developed in Smalltalk
https://www.researchgate.net/publication/328509577_Two_Decades_of_Smalltalk_VM_Development_Live_VM_Development_through_Simulation_Tools


> > Regards,
> >
> > -Martin
> >
> >
>
>
>

-- 
_,,,^..^,,,_
best, Eliot
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