Split buildPythonPackage into setup hooks

This commit splits the `buildPythonPackage` into multiple setup hooks.

Generally, Python packages are built from source to wheels using `setuptools`.
The wheels are then installed with `pip`. Tests were often called with
`python setup.py test` but this is less common nowadays. Most projects
now use a different entry point for running tests, typically `pytest`
or `nosetests`.

Since the wheel format was introduced more tools were built to generate these,
e.g. `flit`. Since PEP 517 is provisionally accepted, defining a build-system
independent format (`pyproject.toml`), `pip` can now use that format to
execute the correct build-system.

In the past I've added support for PEP 517 (`pyproject`) to the Python
builder, resulting in a now rather large builder. Furthermore, it was not possible
to reuse components elsewhere. Therefore, the builder is now split into multiple
setup hooks.

The `setuptoolsCheckHook` is included now by default but in time it should
be removed from `buildPythonPackage` to make it easier to use another hook
(curently one has to pass in `dontUseSetuptoolsCheck`).

1 files changed, 18 insertions, 1 deletions

diff --git a/doc/languages-frameworks/python.section.md b/doc/languages-frameworks/python.section.md
index 4963c97a6c9a..88dc42ebc6c2 100644
--- a/doc/languages-frameworks/python.section.md
+++ b/doc/languages-frameworks/python.section.md
@@ -540,7 +540,8 @@ and the aliases
 #### `buildPythonPackage` function
 
 The `buildPythonPackage` function is implemented in
-`pkgs/development/interpreters/python/build-python-package.nix`
+`pkgs/development/interpreters/python/mk-python-derivation`
+using setup hooks.
 
 The following is an example:
 ```nix
@@ -797,6 +798,22 @@ such as `ignoreCollisions = true` or `postBuild`. If you need them, you have to
 Python 2 namespace packages may provide `__init__.py` that collide. In that case `python.buildEnv`
 should be used with `ignoreCollisions = true`.
 
+#### Setup hooks
+
+The following are setup hooks specifically for Python packages. Most of these are
+used in `buildPythonPackage`.
+
+- `flitBuildHook` to build a wheel using `flit`.
+- `pipBuildHook` to build a wheel using `pip` and PEP 517. Note a build system (e.g. `setuptools` or `flit`) should still be added as `nativeBuildInput`.
+- `pipInstallHook` to install wheels.
+- `pytestCheckHook` to run tests with `pytest`.
+- `pythonCatchConflictsHook` to check whether a Python package is not already existing.
+- `pythonImportsCheckHook` to check whether importing the listed modules works.
+- `pythonRemoveBinBytecode` to remove bytecode from the `/bin` folder.
+- `setuptoolsBuildHook` to build a wheel using `setuptools`.
+- `setuptoolsCheckHook` to run tests with `python setup.py test`.
+- `wheelUnpackHook` to move a wheel to the correct folder so it can be installed with the `pipInstallHook`.
+
 ### Development mode
 
 Development or editable mode is supported. To develop Python packages