[Python-ideas] Integrate some itertools into the Python syntax

[Michel Desmoulin]

Le 22/03/2016 20:23, Ethan Furman a écrit :
> On 03/22/2016 12:10 PM, Koos Zevenhoven wrote:
>> On Tue, Mar 22, 2016 at 8:41 PM, Ethan Furman <ethan at stoneleaf.us> wrote:
>>> On 03/22/2016 10:51 AM, Michel Desmoulin wrote:
>>>
>>>> def foo(p):
>>>>       with open(p) as f:
>>>>           def begin:
>>>>               return x == "BEGIN SECTION"
>>>>            def end:
>>>>               return x == "STOP"
>>>>           return f[begin, end][:10000]
>>>>
>>>> It's very clean, very convenient, very natural, and memory efficient.
>>>
>>>
>>> Except the 10,000 limit doesn't happen until /after/ the end block is
>>> reached -- which could be a million lines later.
>>
>>
>> if f[begin, end] is a generator, the 10000 limit may happen before the
>> end block is reached, which I think was the point.
> 
> That is wrong, which was my point: the `[:10000]` doesn't take effect
> until after `f[begin:end]` (whatever it is) is evaluated.
> 
> -- 
> ~Ethan~

[begin, end] and [:10000] are applied one next() at a time.

begin, then end, then :10000 for the first next(),

then again in that order for the following next() call, etc.

That's the whole point.

> 
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> https://mail.python.org/mailman/listinfo/python-ideas
> Code of Conduct: http://python.org/psf/codeofconduct/