__next__ and StopIteration
Ned Batchelder
ned at nedbatchelder.com
Mon Feb 9 20:30:21 EST 2015
On 2/9/15 2:24 PM, Ned Batchelder wrote:
> On 2/9/15 2:14 PM, Charles Hixson wrote:
>> I'm trying to write a correct iteration over a doubly indexed container,
>> and what I've got so far is: def __next__ (self):
>> for row in range(self._rows):
>> for col in range(self._cols):
>> if self._grid[row][col]:
>> yield self._grid[row][col]
>> #end if
>> #end for col
>> #end for row
>> raise StopIteration
>>
>> What bothers me is that it doesn't look like it would continue to raise
>> StopIteration if it were called again, which is what
>> https://docs.python.org/3/library/stdtypes.html#iterator.__next__ says
>> is correct. How should this be fixed?
>
> You are using yield, which means __next__ is a generator. As such, you
> don't have to explicitly raise StopIteration at all. Just remove that
> statement, and you should be fine.
>
> Also, look into how you are posting, the code is nearly mangled. :(
>
Oops, __next__ isn't right here, it should be __iter__:
def __iter__(self):
for row in range(self._rows):
for col in range(self._cols):
if self._grid[row][col]:
yield self._grid[row][col]
--
Ned Batchelder, http://nedbatchelder.com
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