[Python-ideas] Migration of /usr/bin/python to python3

[Ryan Gonzalez]

Bad idea? What about when you're running simple scripts you've downloaded
and Python 3 is on an external hard drive, not /usr/bin?

That's my usage case, anyway.

On Wed, Mar 11, 2015 at 5:41 PM, Gregory P. Smith <greg at krypto.org> wrote:

> I think /usr/bin/env is a bad idea to promote. It changes from an explicit
> designation of what you need in order to execute to something being derived
> from the users $PATH.  It is *less specific* than /usr/bin/python. For some
> people that is the goal, but I discourage it.
>
> I do agree with Donald (and Nick from the other conversation elsewhere)
> that once this is framed as "the OS won't have Python 2.7 installed at all"
> it is a much better idea: Yes, we will eventually need to update PEP 394 to
> recommend under what circumstances /usr/bin/python -> python3.6 is
> acceptable. (it should never change meaning on a given OS release based on
> the packages installed and 2.7 won't be required for the default install
> images so 3.x makes sense)
>
> The harsh reality is that anyone who does not explicitly specify a
> specific X.Y version of Python in their #! line via has effectively
> declared that they do not care, consequences be damned.  If your code
> supports multiple versions, fixing up the #! line to use the locally
> appropriate one is an install time task.
>
> -gps
>
> On Wed, Mar 11, 2015 at 1:38 PM M.-A. Lemburg <mal at egenix.com> wrote:
>
>> On 11.03.2015 21:03, David Mertz wrote:
>> > https://www.python.org/dev/peps/pep-0394/
>>
>> I think the migration should start with modifying scripts to use
>>
>> #!/usr/bin/env python2
>>
>> when they are Python 2 only (*) and
>>
>> #!/usr/bin/env python3
>>
>> when they are Python 3 only and
>>
>> #!/usr/bin/env python
>>
>> only when they support both Python 2 and 3.
>>
>> "Explicit is better than implicit" and all that Zen :-)
>>
>> Once that's done, switching the symlink is really a no-brainer.
>>
>> The recipe for this is easy too:
>>
>> 1. replace all "#!/usr/bin/env python" with "#!/usr/bin/env python2"
>> 2. migrate your scripts one by one to either Python 3.x or
>>    to Python 2.7 + 3.4+
>> 3. after migration replace "#!/usr/bin/env python2" with
>>    "#!/usr/bin/env python3" or "#!/usr/bin/env python" resp.
>>
>> (*) Some OSes may require to use python2.7, if they don't come
>> with a symlink from python2 -> python2.7.
>>
>> --
>> Marc-Andre Lemburg
>> eGenix.com
>>
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-- 
Ryan
[ERROR]: Your autotools build scripts are 200 lines longer than your
program. Something’s wrong.
http://kirbyfan64.github.io/
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