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Groups > comp.lang.python > #32956

Re: isinstance(.., file) for Python 3

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Duncan Booth, 08.11.2012 14:58:
> Ulrich Eckhardt wrote:
>> If possible, I'm looking for a solution that works for Pythons 2 and 3, 
>> since I'm not fully through the conversion yet and have clients that 
>> might use the older snake for some time before shedding their skin.
>>
>> Suggestions?
> 
> Why bother checking types at all?
> 
> def foo(file_or_string):
>     try:
>         data = file_or_string.read()
>     except AttributeError:
>         data = file_or_string
>     ... use data ...

Or, a tiny bit more safely:

    try:
        read = file_or_string.read
    except AttributeError:
        data = file_or_string
    else:
        data = read()

I'd rather go with one of the previous solutions, though.

Stefan

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Thread

isinstance(.., file) for Python 3 Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-11-08 13:05 +0100
  Re: isinstance(.., file) for Python 3 MRAB <python@mrabarnett.plus.com> - 2012-11-08 12:54 +0000
  Re: isinstance(.., file) for Python 3 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-11-08 12:56 +0000
  Re: isinstance(.., file) for Python 3 Chris Angelico <rosuav@gmail.com> - 2012-11-08 23:57 +1100
  Re: isinstance(.., file) for Python 3 Peter Otten <__peter__@web.de> - 2012-11-08 14:02 +0100
  Re: isinstance(.., file) for Python 3 Duncan Booth <duncan.booth@invalid.invalid> - 2012-11-08 13:58 +0000
    Re: isinstance(.., file) for Python 3 Stefan Behnel <stefan_ml@behnel.de> - 2012-11-08 16:14 +0100

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