Frank Millman wrote:
> Hi all
>
> Python 3.4.1
>
> Here is a simple generator -
>
> def test():
> print('start')
> for i in range(5):
> yield i
> print('done')
>
> x = test()
> for j in x:
> print(j)
>
> As expected, the output is -
>
> start
> 0
> 1
> 2
> 3
> 4
> done
>
> Here I break the loop -
>
> x = test()
> for j in x:
> print(j)
> if j == 2:
> break
>
> Now the output is -
>
> start
> 0
> 1
> 2
>
> 'done' does not appear, so the generator does not actually terminate. What
> happens to it?
>
> My guess is that normal scoping rules apply. Using my example, the
> generator is referenced by 'x', so when 'x' goes out of scope, the
> generator is garbage collected, even though it never completed.
>
> Is this correct?
Yes. In newer Pythons try...finally works, so you can see for yourself:
>>> def f():
... try:
... for c in "abc": yield c
... finally:
... print("done")
...
>>> g = f()
>>> for c in g:
... print(c)
... if c == "b": break
...
a
b
>>> del g
done
Also:
>>> g = f()
>>> next(g)
'a'
>>> g.throw(GeneratorExit)
done
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in f
GeneratorExit
--
https://mail.python.org/mailman/listinfo/python-list
