Multiple versions of Python coexisting in the same OS

[Edward Diener]

On 7/25/2010 8:41 PM, Steven D'Aprano wrote:
> On Sun, 25 Jul 2010 15:19:53 -0400, Edward Diener wrote:
>
>> On 7/25/2010 10:03 AM, Thomas Jollans wrote:
>>> On 07/25/2010 02:46 PM, Edward Diener wrote:
>>>> The problem with this is that you forget that a script can invoke
>>>> Python internally. So whether one uses the console or file association
>>>> method of invoking Python externally, any already written script can
>>>> use either internally.
>>>
>>> Maybe it's just me, but I think that a script that does this is quite
>>> simply badly written: it *will* break on systems that have multiple
>>> Python versions.
>>
>> Whether it is badly written or not in your opinion it is legal and
>> happens all the time.
>
> Yes, people write poorly written, buggy scripts all the time. Just
> because code is legal syntax doesn't mean it does what is intended, or
> that what is intended is sensible.
>
> If you have multiple versions of Python installed, and you call "python
> somescript.py" without knowing *which* Python will be called, it is
> neither sensible nor does it do what you intend. End of story.

Somebody is supplying you with a Python script and internally invoking 
Python again. But that somebody does not have to be myself.

I am neither buying "End of story" nor that invoking Python internally 
is an error. But if you believe it to be then you can root out all such 
Python code, or correct it as you like. Even with co-existing versions 
of Python installed I have better things to do with my time and 
therefore will pursue a solution that will work for me in the face of 
such code.