[Python-Dev] Stackless Python
"Martin v. Löwis"
martin at v.loewis.de
Mon May 31 17:25:12 EDT 2004
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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