[Python-Dev] PEP 3142: Add a "while" clause to generator expressions

[Gerald Britton]

I wonder if this is a bug?

On Tue, Jan 20, 2009 at 11:32 AM, Vitor Bosshard <algorias at yahoo.com> wrote:
> ----- Mensaje original ----
>> De: "python-3000 at udmvt.ru" <python-3000 at udmvt.ru>
>> Para: Gerald Britton <gerald.britton at gmail.com>
>> CC: python-dev at python.org
>> Enviado: martes, 20 de enero, 2009 11:18:24
>> Asunto: Re: [Python-Dev] PEP 3142: Add a "while" clause to generator expressions
>>
>> May I suggest you this variant?
>>
>>     def raiseStopIteration():
>>         raise StopIteration
>>
>>     g = (n for n in range(100) if n*n < 50 or raiseStopIteration())
>>
>> Well, there are more characters...
>>
>> But it is not using any syntax changes and does not require any approval
>> to be functional. Yet it is as fast as the proposed variant, does not require
>> modules and, I hope, will not confuse you or anyone else.
>>
>
> This works as a generator, but not as a list comprehension. The exception is propagated instead of just cutting short the loop:
>
>>>> def r(): raise StopIteration
>>>> print [i for i in range(10) if i**2 < 50 or r()]
> Traceback (most recent call last):
>   File "<pyshell#2>", line 1, in <module>
>     print [i for i in range(10) if i**2 < 50 or r()]
>   File "<pyshell#1>", line 1, in r
>     def r(): raise StopIteration
> StopIteration
>>>>
>
>
> Vitor
>
>
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