A Proposal for Project Layers

Dan Ingalls Dan.Ingalls at disney.com
Tue Nov 16 06:19:10 UTC 1999


>David -
>
>A fresh perspective!  I don't see why we couldn't do this, but now is certainly the time to make sure it would be possible.  I need to think some more before proposing how to do it.

OK.  I just thought some more about it.  Normally we have an open access path somewhat like the following...

	Package
	    SmalltalkPackage
	        SoundPackage

where Package defines the semantics of a layer and each level below adds some bindings and some export methods.  In particular the SmalltalkPackage level "is" the Smalltalk dictionary with all the kernel classes like Object, Collection, etc.

I believe your needs would be fairly well served simply by another direct descendent of the relatively abstract Package class

	Package
	    MinimalTalkPackage
	        MinimalSoundPackage

I don't see any reason you couldn't define a class Object in the MinimalTalk package, with a subclass Collection, and continue on defining other subclasses of it with full support of the existing system, but with the emergent structure being pretty much self-referent.  When it came time to run things, there would be some problems with the primitve objects known to the VM, but I bet you could get pretty far with a special version of the Context stepping simulator.  When that worked, then a carefully crafted trip through the SystemTracer should give you an image that would run with the current VM.

	- Dan





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