Re: policy 2.3 para 2

[Julian Gilbey <J.D.Gilbey@qmul.ac.uk>]

On Mon, Feb 11, 2002 at 10:19:56PM +1100, Donovan Baarda wrote:
> > > Why not take the emacsen-common method and code and use this for
> > > python?  It probably won't work for C-extension modules, but it could
> > > make life easier for pure Python ones.
> 
> Just a thought; since we already have a database of packages in the form of
> the dpkg database, is it possible to do something simple using it instead of
> introducing some other database? As an example, can a python package call
> "dpkg-reconfigure" for all installed packages that depend on "python" in
> its postinst script?

You have two cases to consider:

(1) Installing/removing pythonX.Y package

(2) Installing/removing a python-depending package

Your suggestion will perhaps work for the former but not for the
latter: every python package which wishes to use this scheme will have
to have postinst code anyway.

It may be that as python is simpler, we can simply have a script in a
python-common package which does something like (pardon me if I get
the python a little wrong) -- this could be rewritten in python, of
course, although there's a little question of which python version
would be used....

#! /bin/sh

<Check to see whether there are any arguments saying to limit the
versions of python used or something similar>

while [ $# -gt 0]; do
    for pyth in /usr/bin/python[12].[0-9]; do
        cd /usr/lib/`basename $pyth`
        ln -s ../python-common/$1 .
        $pyth -c "import py_compile; py_compile.compile('$1');
                  py_compile.compile('$1','${1}o');"
    done
done

and a similar one for a package removal.  Then on installation, a
python-module providing package could say in its postinst:

debian-python-compile foo.py bar.py wibble.py wobble.py

and install these modules into /usr/lib/python-common.

Or alternatively, just install them all into /usr/lib/python-common
and run python-update-install, which is essentially the same as the
above but doesn't take filename arguments and does the following
instead:

for pyth in /usr/bin/python[12].[0-9]; do
    cd /usr/lib/`basename $pyth`
    for module in /usr/lib/python-common/*.py; do
        module=`basename $module`
        if [ -L $module ]; then continue; fi
        ln -s ../python-common/$module .
        $pyth -c "import py_compile; py_compile.compile('$module');
                  py_compile.compile('$module','${module}o');"
    done
done

However, that doesn't handle the case of removing packages.  This
could be done using dpkg as you suggest: in the prerm, call
python-update-remove $pkg, and this does the following:

for pyth in /usr/bin/python[12].[0-9]; do
    cd /usr/lib/`basename $pyth`
    for module in dpkg -L $pkg | grep '^/usr/lib/python-common/.*\.py$'; do
        module=`basename $module`
        if [ -L $module ]; then
            rm -f $module ${module}c ${module}o
        fi
    done
done

Now that's seriously easier than the emacsen-common solution, and is
possibly adequate for this situation.

   Julian

-- 
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     Julian Gilbey, Dept of Maths,             Debian GNU/Linux Developer
      Queen Mary, Univ. of London         see http://people.debian.org/~jdg/
   http://www.maths.qmul.ac.uk/~jdg/           or http://www.debian.org/
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