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Mon May 31 17:25:12 EDT 2004 · http://mail.python.org/pipermail/python-dev/2004-May/045044.html

Bob Ippolito wrote:

> I'm believe that map and filter are non-recursive

Can you point me to the code that demonstrates this? Looking at 
Stackless' src/Python/bltinmodule.c:builtin_map, I see

         for (i = 0; ; ++i) {
		...
                 value = PyEval_CallObject(func, alist);
                 ...
		PyList_SetItem(result, i, value)
		...
	}

which looks recursive to me.

> I am not sure about 
> unicode encode/decode.  I don't think it's very common to do a tasklet 
> switch in the middle of a unicode encode or decode, though :)

I thought Stackless was not only about tasklet switching, but also
about running without stack... Wouldn't it perform the "hard" switching
if the stack is running too deep?

>> Py-func1() -> C-func1() -> Py-func2() -> switch to new tasklet
>>               Py-func3() -> C-func2() -> throw exception()
> 
> 
> I don't see how it could cause problems unless this is valid:
>     Py_Func1 -> CPlusPlus_ExceptionCatcher -> Py_Func2 -> 
> CPlusPlus_ExceptionThrower -> throws exception()

It crashes in the process of throwing the exception - not because
it finds no exception handler. It crashes because the internal
data structures have been corrupted.

I should have better made this example:

Py-func1() -> C-func1() -> Py-func2() -> switch to new tasklet
        Py-func3() -> Exception-Catcher -> C-func2() -> throw exception()

> If that *is* valid, how the heck does Py_Func2 get cleaned up?  I have 
> to admit that I'm not very familiar with C++'s implementation of 
> exceptions.

Throwing exceptions through Python functions is not supported, indeed.
However, I was trying to point out that the entire exception handling
mechanism gets corrupted, even if there are valid handlers on the
stack.

Regards,
Martin

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[Python-Dev] Stackless Python