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

Sven Van Caekenberghe sven at stfx.eu
Thu Jan 17 10:57:53 EST 2019



> 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

> Regards,
> 
> -Martin
> 
> 




More information about the Pharo-dev mailing list