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

[pythonewbie]

Hi all,

I am newbie in Python, my wish would be to create python applications
for both Linux/Win32.

I am stucked on creating a function to get the Python install
directory (and site-packages directory) with a 100% reliable method...

My goal is to verify if an/several extension(s) are installed and to
automatically install the missing ones on Linux or Win32.

I have tested sys.executable and sys.path, but I am not sure to be
able to get what I need on different versions of Python and different
platforms.

Google was not a good friend on this, so I am very interested on how
you implement such a function.

Cheers.

[Christian Heimes]

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

[pythonewbie]

On 20 jan, 12:20, Christian Heimes <[e-mail]:

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 ?

[Diez B. Roggisch]

pythonewbie schrieb:

On 20 jan, 12:20, Christian Heimes <[e-mail]:

>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

[pythonewbie]

On 20 jan, 19:50, "Diez B. Roggisch" <[e-mail]:

pythonewbie schrieb:

On 20 jan, 12:20, Christian Heimes <[e-mail]:

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.

[Michael L Torrie]

pythonewbie wrote:

Hi all,

I am newbie in Python, my wish would be to create python applications
for both Linux/Win32.

I am stucked on creating a function to get the Python install
directory (and site-packages directory) with a 100% reliable method...

My goal is to verify if an/several extension(s) are installed and to
automatically install the missing ones on Linux or Win32.

I have tested sys.executable and sys.path, but I am not sure to be
able to get what I need on different versions of Python and different
platforms.

Google was not a good friend on this, so I am very interested on how
you implement such a function.

On both windows and Linux, installing stuff into the python install dir
requires root or administrative privileges, something most linux users
won't have unless they sudo. So if the extensions you need are missing,
and you are distributing them yourself, why not just add them into the
path at runtime, rather than messing with the user's system?

As for obtaining the installation path, the setup.py that often comes
with python modules like ldaptor, seems to be able to figure it out.
I'd check there. I think setup.py is created with distutils.

>
Cheers.

[=?ISO-8859-1?Q?=22Martin_v=2E_L=F6wis=22?=]

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.

The Python install directory is available as sys.prefix. The
site-packages directory is
sys.prefix+"lib/python"+x.y+"/site-packages (where x.y is from
sys.version_info).

HTH,
Martin

[pythonewbie]

On 20 jan, 23:19, "Martin v. Löwis" <[e-mail]:

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.

The Python install directory is available as sys.prefix. The
site-packages directory is
sys.prefix+"lib/python"+x.y+"/site-packages (where x.y is from
sys.version_info).

HTH,
Martin

http://forum.ubuntu-fr.org/viewtopic.php?id=184199

>>import distutils.sysconfig
distutils.sysconfig.get_python_lib()

'/usr/lib/python2.5/site-packages'

get_python_lib(plat_specific=0, standard_lib=0, prefix=None)
Return the directory containing the Python library (standard
or
site additions).

If 'plat_specific' is true, return the directory containing
platform-specific modules, i.e. any module from a non-pure-
Python
module distribution; otherwise, return the platform-shared
library
directory. If 'standard_lib' is true, return the directory
containing standard Python library modules; otherwise, return
the
directory for site-specific modules.

If 'prefix' is supplied, use it instead of sys.prefix or
sys.exec_prefix -- i.e., ignore 'plat_specific'.

[Diez B. Roggisch]

pythonewbie

>
Because the solution using distutils.sysconfig.get_python_lib() is
very smart !

Depending on your goal. You said

"""
My goal is to verify if an/several extension(s) are installed and to
automatically install the missing ones on Linux or Win32.
"""

This goal can't be reached with only the site-packages - because I can
install packages somewhere else (matter of factly, this happens on debian
for example, they've split the install-dirs and created a bunch of dirs
under /usr/share)

So having a method that gives you the installation root doesn't help much
here.

Diez

[pythonewbie]

On 21 jan, 10:34, "Diez B. Roggisch" <[e-mail]:

pythonewbie

Because the solution using distutils.sysconfig.get_python_lib() is
very smart !

Depending on your goal. You said

"""
My goal is to verify if an/several extension(s) are installed and to
automatically install the missing ones on Linux or Win32.
"""

This goal can't be reached with only the site-packages - because I can
install packages somewhere else (matter of factly, this happens on debian
for example, they've split the install-dirs and created a bunch of dirs
under /usr/share)

So having a method that gives you the installation root doesn't help much
here.

Diez

To John Machin,

>>sys.path

['', '/usr/lib/python25.zip', '/usr/lib/python2.5', '/usr/lib/
python2.5/plat-linux2', '/usr/lib/python2.5/lib-tk', '/usr/lib/
python2.5/lib-dynload', '/usr/local/lib/python2.5/site-packages', '/
usr/lib/python2.5/site-packages', '/usr/lib/python2.5/site-packages/
Numeric', '/usr/lib/python2.5/site-packages/gst-0.10', '/var/lib/
python-support/python2.5', '/usr/lib/python2.5/site-packages/gtk-2.0',
'/var/lib/python-support/python2.5/gtk-2.0', '/usr/lib/python2.5/site-
packages/wx-2.8-gtk2-unicode']