On 02/10/2015 08:53 AM, Ian Kelly wrote:
> On Tue, Feb 10, 2015 at 9:44 AM, Ethan Furman wrote:
>> On 02/09/2015 08:46 PM, Chris Angelico wrote:
>>>
>>> class Grid:
>>> blah blah
>>>
>>> def __iter__(self):
>>> for row in range(self._rows):
>>> for col in range(self._co
On Tue, Feb 10, 2015 at 12:30 AM, Ian Kelly wrote:
>
> On Mon, Feb 9, 2015 at 5:59 PM, Chris Kaynor wrote:
> > On Mon, Feb 9, 2015 at 4:42 PM, Steven D'Aprano
> > wrote:
> >> so that's an excellent sign that doing so is best practice, but it should
> >> not be seen as *required*. After all, perh
On Tue, Feb 10, 2015 at 9:44 AM, Ethan Furman wrote:
> On 02/09/2015 08:46 PM, Chris Angelico wrote:
>>
>> class Grid:
>> blah blah
>>
>> def __iter__(self):
>> for row in range(self._rows):
>> for col in range(self._cols):
>> if self._grid[row][col]:
>>
On 02/09/2015 08:46 PM, Chris Angelico wrote:
>
> class Grid:
> blah blah
>
> 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]
I strongly sug
On Mon, Feb 9, 2015 at 5:59 PM, Chris Kaynor wrote:
> On Mon, Feb 9, 2015 at 4:42 PM, Steven D'Aprano
> wrote:
>> so that's an excellent sign that doing so is best practice, but it should
>> not be seen as *required*. After all, perhaps you have good reason for
>> wanting your iterable class to o
On Tue, Feb 10, 2015 at 5:16 PM, Charles Hixson
wrote:
> Yes, rows and cols are lists, but I'm going to need to iterate through them
> more than once. I'd rather do without a included class, but if a properly
> formed iterator can only be cycled through once, and if I understand
> properly that m
On 02/09/2015 08:46 PM, Chris Angelico wrote:
On Tue, Feb 10, 2015 at 3:33 PM, Charles Hixson
wrote:
The proper version of the "hard way" is:
1) The __iter__ method of the iterable constructs a new iterator
instance and returns it.
2) The __iter__ method of the *iterator* simply returns itse
Chris Kaynor wrote:
> On Mon, Feb 9, 2015 at 4:42 PM, Steven D'Aprano
> wrote:
>> so that's an excellent sign that doing so is best practice, but it should
>> not be seen as *required*. After all, perhaps you have good reason for
>> wanting your iterable class to only be iterated over once.
>
>
On Tue, Feb 10, 2015 at 3:33 PM, Charles Hixson
wrote:
>> The proper version of the "hard way" is:
>>
>> 1) The __iter__ method of the iterable constructs a new iterator
>> instance and returns it.
>>
>> 2) The __iter__ method of the *iterator* simply returns itself.
>>
>> 3) The __next__ method o
On 02/09/2015 03:56 PM, Ian Kelly wrote:
On Mon, Feb 9, 2015 at 4:30 PM, Steven D'Aprano
wrote:
The way you write iterators is like this:
Method 1 (the hard way):
- Give your class an __iter__ method which simply returns self:
def __iter__(self):
return self
- Give your clas
On Tue, Feb 10, 2015 at 12:11 PM, Steven D'Aprano
wrote:
>> Yes, it is allowed. But when you write code that's documented as being
>> "broken", you should expect annoying, subtle errors, maybe a long way
>> down the track.
>
> Well, that depends, don't it?
>
> Am I really going to care if the iter
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 rowinrange(self._rows):
for col in range(self._cols):
Chris Angelico wrote:
> On Tue, Feb 10, 2015 at 11:42 AM, Steven D'Aprano
> wrote:
>> Also, *technically* iterators may be re-iterable. The docs say that
>> iterators which fail to raise StopIteration forever once they are
>> exhausted are "broken", but the docs do not forbid broken iterators.
>>
On Mon, Feb 9, 2015 at 4:42 PM, Steven D'Aprano
wrote:
> so that's an excellent sign that doing so is best practice, but it should
> not be seen as *required*. After all, perhaps you have good reason for
> wanting your iterable class to only be iterated over once.
In fact, there is one in the std
On Tue, Feb 10, 2015 at 11:42 AM, Steven D'Aprano
wrote:
> Also, *technically* iterators may be re-iterable. The docs say that
> iterators which fail to raise StopIteration forever once they are exhausted
> are "broken", but the docs do not forbid broken iterators. Consenting
> adults and all that
Ian Kelly wrote:
> On Mon, Feb 9, 2015 at 4:30 PM, Steven D'Aprano
> wrote:
[...]
>> Your class is itself an iterator.
>
> This is an anti-pattern, so don't even suggest it. Iterables should
> never be their own iterators. Otherwise, your iterable can only be
> iterated over once!
Hmmm, good po
On Mon, Feb 9, 2015 at 4:30 PM, Steven D'Aprano
wrote:
> The way you write iterators is like this:
>
>
> Method 1 (the hard way):
>
> - Give your class an __iter__ method which simply returns self:
>
> def __iter__(self):
> return self
>
> - Give your class a __next__ method (`next` in
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 rowinrange(self._rows):
> for col in range(self._cols):
> if self._grid[row][col]:
>
On Mon, 09 Feb 2015 11:14:55 -0800, 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 rowinrange(self._rows):
> for col in range(self._cols):
>
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 rowinrange(self._rows):
for col in range(self._cols):
if self._grid[row][col]:
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 rowinrange(self._rows):
for col in range(self._cols):
if self._grid[row][col]:
yieldself._grid[row]
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