En Tue, 15 Apr 2008 20:26:16 -0300, Yves Dorfsman <[EMAIL PROTECTED]>
escribió:
> Dan Bishop wrote:
>
>>>> lines[:] = [line.rstrip('\n') for line in lines]
>>> What is the point of the [:] after lines ? How different is it with or
>>> without it ?
>>
>> It causes the result to be stored in the existing list.
>>
>
> If we do:
> lines = [line.rstrip('\n') for line in lines]
>
> lines is now a new list, the old list as no reference to it, and will be
> discarded by the gc, right ? So we're not really saving any space here ?
>
> If we do:
> lines[:] = [line.rstrip('\n') for line in lines]
>
> We reuse an existing list, therefore we are saving the time it takes to
> create a new list ? So this is a performance issue ?
No. The new list (the right hand side) is created in either case, so there
is no difference here. And the name `lines` refers to a list with the new
contents in all cases. The difference is on whether *other* references to
the original list see the changes or not.
For an example, see Dan Bishop's message earlier on this thread.
--
Gabriel Genellina
--
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