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Date: Thu, 28 Nov 2013 08:04:13 -0600
From: Tim Chase <python.list@tim.thechases.com>
To: python-list@python.org
Subject: Re: Python and PEP8 - Recommendations on breaking up long lines?
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Xref: csiph.com comp.lang.python:60688

On 2013-11-28 03:58, Steven D'Aprano wrote:
>>      input = open(self.full_path)
>>      output = open(self.output_csv, 'ab')
>>      with input as input, output as output:
>>          ...
> 
> That's really clever! Why didn't I think of that?

Because if the 2nd output fails, the input doesn't get closed as
it {w,sh}ould in a with-statement? :-)

You could work around this with:

  from functools import partial
  in_ = partial(open, self.full_path)
  out_ = partial(open, self.output_csv, 'ab')
  with in_() as input, out_() as output:
    do_stuff()

There's still room for programmer error if you don't have an
"output_csv" property on self and you get an AttributeError, but
that's more of a "dumb programmer error" rather than an actual
runtime exception.

-tkc