Groups > comp.lang.python > #19275

Re: Looking under Python's hood: Will we find a high performance or clunky engine?

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Date	Mon, 23 Jan 2012 10:56:49 -0800 (PST)
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在 2012年1月23日星期一UTC+8上午2时01分11秒，Robert Kern写道：
> On 1/22/12 3:50 PM, Rick Johnson wrote:
> >
> > What does Python do when presented with this code?
> >
> > py>  [line.strip('\n') for line in f.readlines()]
> >
> > If Python reads all the file lines first and THEN iterates AGAIN to do
> > the strip; we are driving a Fred flintstone mobile. If however Python
> > strips each line of the lines passed into readlines in one fell swoop,
> > we made the correct choice.
> >
> > Which is it Pythonistas? Which is it?
> 
> The .readlines() method is an old API that predates the introduction of 
> iterators to Python. The modern way to do this in one iteration is to use the 
> file object as an iterator:
> 
>    [line.strip('\n') for line in f]

This is more powerful by turning an object to be iterable.

But the list comprehension violates the basic operating 
principle of the iteratee chaining rule in programming.
 
I know manny python programmers just abandon the list comprehension
in non-trivial processes.

Thread

Looking under Python's hood: Will we find a high performance or clunky engine? Rick Johnson <rantingrickjohnson@gmail.com> - 2012-01-22 07:50 -0800
  Re: Looking under Python's hood: Will we find a high performance or clunky engine? Heiko Wundram <modelnine@modelnine.org> - 2012-01-22 18:52 +0100
  Re: Looking under Python's hood: Will we find a high performance or clunky engine? Robert Kern <robert.kern@gmail.com> - 2012-01-22 18:01 +0000
    Re: Looking under Python's hood: Will we find a high performance or clunky engine? 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-23 10:56 -0800
    Re: Looking under Python's hood: Will we find a high performance or clunky engine? 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-23 10:56 -0800
      Re: Looking under Python's hood: Will we find a high performance or clunky engine? alex23 <wuwei23@gmail.com> - 2012-01-23 22:44 -0800
        Re: Looking under Python's hood: Will we find a high performance or clunky engine? Chris Angelico <rosuav@gmail.com> - 2012-01-24 19:14 +1100
  Re: Looking under Python's hood: Will we find a high performance or clunky engine? Michael Torrie <torriem@gmail.com> - 2012-01-22 17:38 -0700
    Re: Looking under Python's hood: Will we find a high performance or clunky engine? Rick Johnson <rantingrickjohnson@gmail.com> - 2012-01-22 17:04 -0800
      Re: Looking under Python's hood: Will we find a high performance or clunky engine? Michael Torrie <torriem@gmail.com> - 2012-01-22 18:32 -0700
  Re: Looking under Python's hood: Will we find a high performance or clunky engine? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-23 09:11 +0000
  Re: Looking under Python's hood: Will we find a high performance or clunky engine? Grant Edwards <invalid@invalid.invalid> - 2012-01-23 16:08 +0000

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