Linux/Win32 func. to get Python instdir (not exedir) + site-packages => extensions mgmt

[Diez B. Roggisch]

pythonewbie schrieb:
> On 20 jan, 20:59, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
>> pythonewbie schrieb:
>>
>>
>>
>>> On 20 jan, 19:50, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
>>>> pythonewbie schrieb:
>>>>> On 20 jan, 12:20, Christian Heimes <li... at cheimes.de> wrote:
>>>>>> pythonewbie wrote:
>>>>>>> I am stucked on creating a function to get the Python install
>>>>>>> directory (and site-packages directory) with a 100% reliable method...
>>>>>> Only one method is 100% reliable:
>>>>>> try:
>>>>>>     import yourextension
>>>>>> except ImportError:
>>>>>>     available = False
>>>>>> else:
>>>>>>     available = True
>>>>>> Christian
>>>>> Hi Christian,
>>>>> OK thanks, interesting to detect if an extension is available or not.
>>>>> But for different reasons I also want to get the absolute path of
>>>>> Python install directory (not only the executable under Linux) and
>>>>> site-packages directory.
>>>>> How could I proceed ?
>>>> Maybe sys.path is a starter?
>>>> Diez
>>> Yes, it is, but my problem is that I am not sure to find the
>>> information I need at the same position of the list generated by
>>> sys.path.
>>> I explain, for Win32, I find install directory using sys.path[6] and
>>> site-package directory using sys.path[7], for Linux I find install
>>> directory using sys.path[2] and site-package directory using
>>> sys.path[6].
>>> For my tests, I have used XP Pro and Ubuntu Gutsy.
>>> I am not sure to find these information at the same position in the
>>> sys.path list using Win9x, Win2k, Ubuntu Dapper, Redhat FC6, FreeBSD
>>> and using Python v2.1 2.2 2.3 etc ?
>>> This why I'm asking experienced programmers of this usenet group for
>>> advices.
>> Sorry, I missed your first post. However, I don't see what your problem
>> actually is. If you want to look for any extension, you need to consider
>> whatever can be seen in the sys.path. So what do you care about the
>> order of them?
>>
>> Diez
> 
> I just would like to know if I would ALWAYS find the install directory
> in sys.path[6] and site-packages directory in sys.path[7] on any Win32
> platform and sys.path[2] and site-packages directory in sys.path[6] on
> any Linux platform.
> 
> If the reply is : "YES you can be sure of it !"
> 
> All would be great for me and I would be ready to create a script to
> detect with a reliable manner the installation dir. et site-packages
> dir. for all my Linux/Win32 Python apps.
> 
> Thanks for your interest on this topic.


I doubt that you can say such things. You can even manipulate the path 
at runtime.

And I still don't understand WHY you want that? If you want 
site-packages, why don't you loop through the paths until you find it?

Diez