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[Python-ideas] sentinel_exception argument to `iter`

Terry Reedy tjreedy at udel.edu
Fri Feb 7 07:03:16 CET 2014 
On 2/6/2014 11:15 PM, Terry Reedy wrote:
>> On Fri, Feb 7, 2014 at 1:36 PM, Terry Reedy

>>> def __next__(self):
>>>    try:
>>>      x = self.func()
>>>    except Exception as exc:
>>>      if isinstance(exc, self.sentinel):
>>>        raise StopIteration from None
>          else:
>            raise

I just realized that the above is unnecessarily complicated because the 
expression that follows 'except' is not limited to a builtin exception 
class name or tuple thereof. (I have never before had reason to 
dynamically determine the exception to be caught.) So, using a third 
parameter, replace the 5 lines with 2.

     except self.stop_exception:
         raise StopIteration from None

>>>    if x == self.sentinel:
>>>      raise StopIteration
>>>    else:
>>>      return x

-- 
Terry Jan Reedy
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