[Chicago] PyCon 2006

Ian Bicking ianb at colorstudy.com
Tue Sep 13 22:57:00 CEST 2005

Brian Ray wrote:
> BTW, what is Stackless?
> Is there a concise definition of Stackless Python?

Stackless: http://stackless.com/
Basically it's a version of Python (defunct at this point, really) where 
the stack becomes a first-class object.  So you can refer to the 
execution-context-as-exists-right-now.  This means things like 
call-with-current-continuation (a Schemism) are possible.

I wrote something on continuations some time back: 
that might be helpful.

You can do things like:

def ask_name():
     name = get_response('name')
     age = get_response('age')
     print 'Hello', name, 'you are', age, 'years old'

Except where get_response() actually sends a web page to the user, waits 
for their response by submitting the form, then returns the value they 
gave.    And if they respond with their name, then hit back, then 
respond again, it'll all work (effectively rewinding the function back 
to the get_response() that they are answering).  This is the big feature 
of systems like Seaside.

Some of what stackless can do will be made possible by PEP 342: 
http://www.python.org/peps/pep-0342.html -- but not stuff like rewinding 
a function.

Ian Bicking  /  ianb at colorstudy.com  /  http://blog.ianbicking.org

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