Uche Ogbuji wrote:
>
> > [Uche Ogbuji]
> > > Quite interesting. I brought up this *exact* point at the
> > > Stackless BOF at IPC9. I mentioned that the immediate reason
> > > I was interested in Stackless was to supercharge the efficiency
> > > of 4XSLT. I think that a stackless 4XSLT could pretty much
> > > annihilate the other processors in the field for performance.
> >
> > Hmm. I'm interested in clarifying the cost/performance boundaries of the
> > various approaches. I don't understand XSLT (I don't even know what it is).
> > Do you grok the difference between full-blown Stackless and Icon-style
> > generators?
>
> To a decent extent, based on reading your posts carefully.
>
> > The correspondent I quoted believed the latter were on-target
> > for XSLT work, and given the way Python works today generators are easier to
> > implement than full-blown Stackless. But while I can speak with some
> > confidence about the latter, I don't know whether they're sufficient for what
> > you have in mind.
>
> Based on a discussion with Christian at IPC9, they are. I should have been
> more clear about that. My main need is to be able to change a bit of context
> and invoke a different execution path, without going through the full overhead
> of a function call. XSLT, if written "naturally", tends to involve huge
> numbers of such tweak-context-and-branch operations.
>
> > If this is some flavor of one-at-time tree-traversal algorithm, generators
> > should suffice.
> >
> > class TreeNode:
> > # with self.value
> > # self.children, a list of TreeNode objects
> > ...
> > def generate_kids(self): # pre-order traversal
> > suspend self.value
> > for kid in self.children:
> > for itskids in kid.generate_kids():
> > suspend itskids
> >
> > for k in someTreeNodeObject.generate_kids():
> > print k
> >
> > So the control-flow is thoroughly natural, but you can only suspend to your
> > immediate invoker (in recursive traversals, this "walks up the chain" of
> > generators for each result). With explicitly resumable generator objects,
> > multiple trees (or even general graphs -- doesn't much matter) can be
> > traversed in lockstep (or any other interleaving that's desired).
> >
> > Now decide <wink>.
>
> Suspending only to the invoker should do the trick because it is typically a
> single XSLT instruction that governs multiple tree-operations with varied
> context.
>
> At IPC9, Guido put up a poll of likely use of stackless features, and it was a
> pretty clear arithmetic progression from those who wanted to use microthreads,
> to those who wanted co-routines, to those who wanted just generators. The
> generator folks were probably 2/3 of the assembly. Looks as if many have
> decided, and they seem to agree with you.
Here the exact facts of the poll:
microthreads: 26
co-routines: 35
generators: 44
I think this reads a little different.
ciao - chris
--
Christian Tismer :^) <mailto:tismer@tismer.com>
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