Exception handling in Python 3.x

[Steve Holden]

On 12/7/2010 5:58 AM, John Nagle wrote:
>    PEP 255, like too much Python literature, doesn't distinguish clearly
> between the language definition and implementation detail. It says
> "The mechanics of StopIteration are low-level details, much like the
> mechanics of IndexError in Python 2.1".  Applications shouldn't be
> explicitly using StopIteration.
>  
So you don't think that we should rely on iterables with no __iter__()
method to raise IndexError to terminate iterations when their
__getitem__() is called with an invalid index? The IndexError mechanism
was, to the best of my less-than-complete knowledge, used by all pre-2.2
implementations. The quoted paragraph appears to be intended to reassure
the applications programmer that there is no normal need to handle
StopIteration specially - just as there was no need to handle IndexError
specially.

>    IronPython doesn't do StopIteration the same way CPython does.
> 
> http://ironpython.codeplex.com/wikipage?title=IPy1.0.xCPyDifferences
> 
Perhaps not, but the only difference is what happens on repeated calls
to next() after the iterator is exhausted. The iterator still terminates
by raising a StopIteration error.

I have no idea what Shed Skin does, but to the extent that iterators
don't raise StopIteration on exhaustion I'd say it is in error.

regards
 Steve
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