On 12/3/2010 5:04 AM, Steven D'Aprano wrote:
Consider the following common exception handling idiom:
def func(iterable):
it = iter(iterable)
try:
x = next(it)
except StopIteration:
raise ValueError("can't process empty iterable")
print(x)
The intention is:
* detect an empty iterator by catching StopIteration;
* if the iterator is empty, raise a ValueError;
* otherwise process the iterator.
Note that StopIteration is an internal detail of no relevance whatsoever
to the caller. Expose this is unnecessary at best and confusing at worst.
Right. You're not entitled to assume that StopIteration is
how a generator exits. That's a CPyton thing; generators were
a retrofit, and that's how they were hacked in. Other implementations
may do generators differently.
John Nagle
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