Multiple versions of Python coexisting in the same OS

[News123]

On 07/25/2010 09:33 PM, Edward Diener wrote:
> On 7/25/2010 10:31 AM, News123 wrote:
>> On 07/25/2010 02:46 PM, Edward Diener wrote:
>>> On 7/25/2010 6:07 AM, Gelonida wrote:

> 
> How does a 'pystarter' program know where the file's location is which
> is being invoked ? 
the file's location would be somewhere in sys.argv
probably in sys.argv[1].
converting it to  an abs path would return a directory which the python
file belongs to.


> As to the first file line this is completely
> unrealistic. What are you going to do, alter the first file line of
> every script in a Python distribution and every script in every library
> installed in a Python distribution ? Sorry, but a less intrusive
> solution is much better and much less of a headache to say the least.
> 
Well I would at least do it for all of my self written scripts.

It could allow a soft transition from 2.6 to 2.7 to 3.0 without having
to upgrade all scripts at the same time.

> My intended solution would be a simple program which understands where
> each co-existing Python distribution is installed on a system and what
> the "name" of that distribution is. Then you tell the program which
> Python distribution should be the current one by its "name", the current
> one meaning the distribution which you want to be invoked at any given
> time. The program then changes the PATH so that any references to the
> Python directory and its subdirectories point to the "name" Python
> directory tree, and changes the file associations so that the "name"
> Python executables handle the Python associations.


> 
> This does have the weakness that I can not use more than one Python
> distribution while Python is executing scripts. But I can personally
> live with that since I have never encountered a situation where I must
> use more than one Python distribution at the same time.
> 

I guess it's rather difficult to find a solution which suits all.

The above minor weakness, that you mention would be a killer for me.

Currently I'm looking for solutions, where I can start python scripts
requireing different python versions at the same time.

Currently I'm staring the scripts manually from two different cmd line
windows with a different path name and an explicit python call,

Thus my idea of having a pystarter with a config file
mentioning which directories (tools) should use which python executable