[Python-Dev] functional continuations

Phillip J. Eby pje at telecommunity.com
Sat Dec 15 17:57:51 CET 2007

At 01:04 AM 12/15/2007 -0800, tomer filiba wrote:
>* do you suppose it will work? are there any drawbacks i didn't

Yes.  :)

Specifically, think about what happens when a C function is in the 
call stack, e.g.:

def f1():
     return map(f2, [1,2,3])

def f2(ob):
     raise WaitFor(something)
     return ob

print f1()

If I understand you correctly, when this program is run, it will 
print "1", rather than "[1, 2, 3]", because there is no way for you 
to keep track of the internal state of the 'map()' call.

And this isn't just a problem for map() -- even something as simple 
as a property access passes through C code whose state can get lost.

I don't think this approach is practical; you'd be better off using a 
co-routine stack and trampoline, since the nature of generators 
naturally forces all the C code out of the picture.

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