[Python-ideas] sentinel_exception argument to `iter`

[Terry Reedy]

On 2/6/2014 9:45 PM, Chris Angelico wrote:
> On Fri, Feb 7, 2014 at 1:36 PM, Terry Reedy <tjreedy at udel.edu> wrote:

>> def __next__(self):
>>    try:
>>      x = self.func()
>>    except Exception as exc:
>>      if isinstance(exc, self.sentinel):
>>        raise StopIteration from None
         else:
           raise
>>    if x == self.sentinel:
>>      raise StopIteration
>>    else:
>>      return x
>
> Forgive me if this is a stupid question, but wouldn't this suppress
> any other thrown exception? I'm looking for a bare 'raise' inside the
> except block,

which should be there. As I said, but you snipped, '(untested)'

> such that any exception is guaranteed to raise
> something, but if it's a subclass of self.sentinel, it raises
> StopIteration instead.

-- 
Terry Jan Reedy