From: Avi Bryant Date: 2005-04-08T19:54:40+09:00 Subject: Re: Seven new VMs, all in a row Robert Feldt wrote: > On Apr 8, 2005 11:54 AM, Avi Bryant wrote: > > http://www.iam.unibe.ch/~ducasse/FreeBooks/CollectiveNBlueBook/oe-tour-sept19.pdf > > > Great, thanks Avi. Can I assume the commercial VMs are similar to this > or do you know of detailed descriptions of them? I don't know of any detailed descriptions. Apart from the obvious fact that they have JITs and the stock Squeak engine doesn't, one difference I know is that VisualWorks still uses an object table rather than direct object references, which makes #become: much faster and probably helps with garbage collection. However, for the purpose of knowing how to model Ruby on top of the VM (the object format, classes and method dictionaries, how context stacks work), they should all be very similar, at least on the surface - never mind what optimizations are going on below. > BTW, wasn't Peter Deutsch himself onto a similar project for Python: > > http://blog.amber.org/2004/08/12/python-on-smalltalks-vm/ Yes, but that's a much harder problem, since Python has very different semantics from Smalltalk, whereas Ruby's are for most purposes identical. Avi