python 2 to 3 conversion

[Igor Korot]

Hi, Chris,

On Mon, Jun 17, 2019 at 9:55 AM Chris Angelico <rosuav at gmail.com> wrote:
>
> On Mon, Jun 17, 2019 at 11:15 PM Igor Korot <ikorot01 at gmail.com> wrote:
> >
> > Hi, Chris et al,
> >
> > On Mon, Jun 17, 2019 at 8:00 AM Chris Angelico <rosuav at gmail.com> wrote:
> > >
> > > On Mon, Jun 17, 2019 at 10:50 PM Thomas Jollans <tjol at tjol.eu> wrote:
> > > >
> > > > On 17/06/2019 15.14, Igor Korot wrote:
> > > > > Hi,
> > > > > Is there a place where there is a full list of incompatibilities between
> > > > > python 2 and python 3 is available and how to fix them?
> > > >
> > > > ‘What’s new in Python 3.0’ is a good starting point
> > > >
> > > > https://docs.python.org/3/whatsnew/3.0.html
> > > >
> > > > It doesn’t list all standard library changes, but it has the most
> > > > important ones. Obviously it can't include anything that third-party
> > > > modules do.
> > > >
> > > > The main incompatibility is obviously strings, and there various modules
> > > > have adopted different strategies for the transition.
> > >
> > > Unfortunately starting there means ignoring all the compatibilities
> > > that were implemented in more recent versions. Notably, Python 3.3
> > > introduced u"..." literals, and 3.5 allows you to use percent
> > > interpolation with bytes as well as text. So those kinds of
> > > differences are no longer significant.
> > >
> > > ChrisA
> >
> > This is what I have in my script (reproduction steps):
> >
> > igor at IgorReinCloud ~/dbhandler/libdbwindow/res/gui $ python
> > Python 3.6.5 (default, Oct  5 2018, 14:32:41)
> > [GCC 7.3.0] on linux
> > Type "help", "copyright", "credits" or "license" for more information.
> > >>> import array
> > >>> bytes = array.array('B', open("bold.png", "rb").read())
> > >>> bytes[0:16].tostring()
> > b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR'
> > >>> if bytes[0:16].tostring() != '\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR':
> > ...     print("Failed")
> > ...
> > Failed
> > >>>
> >
> > Do I just need to add "b" in front of the string to make it work with both?
> > Or I need to check version call?
> >
>
> Yep, all you need to do is compare against a byte string. That should
> be the only change needed. Currently, you're checking against a byte
> string in Py2, and a text string in Py3; but the b"..." prefix will
> make them consistent.

Thank you.
I will try to test it tonight pulling my python 2 install.

>
> ChrisA
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