Re: Python installation paths

[Richard Laager]

On 6/2/22 14:15, Alec Leamas wrote:

Hi Audrey

On 02/06/2022 20:16, Andrey Rahmatullin wrote:

On Thu, Jun 02, 2022 at 07:19:56PM +0200, Alec Leamas wrote:

Dear list,

I try handle a package which installs a partly compiled,
architecture-dependent python module. Until now  this has been done in

fine.


this installation path is not in sys.path by default.


exact way to install code like this, in the policy [2]
parlance an "extension module".

/usr/lib/triplet/python3.10/site-packages. This scheme has basically worked However, here is an Ubuntu bug [1] where a user runs into problems because I have been trying to look in the python policy docs, but cannot find the

Not sure where is this documented but you can easily check on your system. It should be /usr/lib/python3/dist-packages/*.cpython-3*-x86_64-linux-gnu.so

Hm...this is not what I have. Did I get get the term "Extension module" wrong?

On an older version, I had this (from the python3-ntp binary package):

/usr/lib/python3/dist-packages/ntp
/usr/lib/python3/dist-packages/ntp/__init__.py
(other .py files omitted)
/usr/lib/python3/dist-packages/ntp/ntpc.cpython-38-x86_64-linux-gnu.so



On newer python3-ntp, using the FFI approach, I have this:

/usr/lib/python3/dist-packages/ntp/__init__.py
/usr/lib/python3/dist-packages/ntp/ntpc.py
(other .py files omitted)
/usr/lib/x86_64-linux-gnu/ntp/libntpc.so
/usr/lib/x86_64-linux-gnu/ntp/libntpc.so.1
/usr/lib/x86_64-linux-gnu/ntp/libntpc.so.1.1.0



I hope that helps.

--
Richard

There are a couple different ways to do Python to C. I think the terms are CFFI (or FFI or ctypes, maybe some of those are different though?) vs CPython extension, but I'm not 100% certain of that. I maintain the ntpsec package. IIRC, upstream is transitioning (but I think still supports both at the moment). I believe that is the extension approach. I think the way this works is that if you import ntpc, it imports the .so. Note that there is no ntpc.py. In this approach, ntpc.py has explicit code to load libntpc.so from /usr/lib/x86_64-linux-gnu/ntp/ (that path being subst'ed in to ntpc.py by the build process).

OpenPGP_signature
Description: OpenPGP digital signature