Python envs did not pass through any of the properties the Python
interpreter has. That could be annoying, especially not having
`python.interpreter` which is the path to the interpreter. This commit
fixes the situation and inherit python.passthru.
python.buildenv is used to build an env that provides binaries that can
import all modules that were passed in to the env.
Before this change it filtered the propagatedBuildInputs to remove all
non-Python packages, thereby possibly reducing the amount of packages
that were referenced. However, Python packages often don't have non-
Python packages as propagatedBuildInputs. And occasionally, we do want
to be able to add other packages to the env.
Currently, when constructing a buildEnv and adding packages via
extraLibs, then binaries in extraLibs cannot access the other Python
modules. An example is having ipython/jupyter in extraLibs; in that case
ipython cannot import any other modules.
The default setting for extraLibs used to be the set of modules that come with
python by default but aren't usually enabled in our standard python derivation
because they require additional libraries. This meant that users who want to
*add* libraries to that set had to use a fairly complicated override, to add
more entries without loosing the ones set by default.
After this patch, the "standard libraries" such as "curses' are listed in
stdLibs while the extraLibs argument remains empty by default. This allows
users to override extraLibs without overriding the standard libraries.
Furthermore, the wrapper environment can be messed around with in an
additional 'postBuild' step. One nice application of this build step is
to patch scripts and binaries to use the wrapped python interpreter
instead of the pristine one, thereby enabling them to pick up all
modules that have been configured. The following example shows how this
is done for the 'pylint' utility:
pkgs.python27Full.override {
extraLibs = [pkgs.pylint];
postBuild = ''
cd ${pkgs.pylint}/bin
for i in *; do
rm $out/bin/$i
sed -r -e "s|^exec |exec $out/bin/python -- |" <$i >$out/bin/$i
chmod +x $out/bin/$i
done;
'';
};
The new wrapper creates an environment that contains all files from
Python and the extra libraries that have been specified. All files are
found at run-time by means of the $PYTHONHOME variable; the wrapper no
longer uses $PYTHONPATH.
The python wrapper expression expects a list of Python modules, $extraLibs,
which are added to $PYTHONPATH before executing the actual Python interpreter.
svn path=/nixpkgs/trunk/; revision=23194
