[gentoo-user] Python: ebuilds vs. pip3 install --user

[Grant Edwards]

Background: a utility written in Python that I use regularly
(weasyprint) was out-of-date and is being dropped from Gentoo's
package database.  I tried (and faield) to creaate an ebuild for a
more recent version.  So I ended up doing

 $ pip3 install --user weasyprint

That installed weasyprint and a few depdendancies (tinycss2,
defusedxml, ciarocffi) under ~/.local/{bin,lib64}.

Question:

Can those dependancies installed under ~/.local cause problems for
things that were installed using standard ebuilds which require
older/other versions of those libraries (which were installed using
standard ebuilds)?

For example, weasyprint requires cairosvg 2.4, and 2.4.2 was installed
under .local via the pip3 command shown above.

My stable cairosvg is 2.0.3 and it is installed in the usual "system"
location /usr/lib64/python3.6/site-packages by the normal "emerge"
process.  [IIRC, at one point I tried unmasking 2.4.2, but that caused
a cascade of other problems.]

Q: Under what conditions will having a second installation of a Python
   library under .local cause problems?

-- 
Grant Edwards               grant.b.edwards        Yow! If I felt any more
                                  at               SOPHISTICATED I would DIE
                              gmail.com            of EMBARRASSMENT!