[Setup] Add support for development install

Context

Add capacity in setup.py to do pip editable installs (or development mode), i.e.:

• modification to python files do not need a reinstallation,
• C++ build can be incrementally rebuild and reinstalled from the build/ directory

In order to use editable mode even with recent versions of python one should do pip install -v --no-build-isolation -e . instead of the default install with pip install -v .

This MR allows editable mode to speedup day to day development basically with the changes:

• moved the installation of the python binding library into the cmake build system, instead of the setup script
• detect editable mode and in this case install the python binding library directly in the source python package

Note that due to behavior changes depending on the python/setuptools versions, the portable method to ensure incremental build on C++ files is to use the first time (pre-install build dependencies, and use --no-build-isolation):

pip install setuptools setuptools_scm[toml] cmake
pip install --no-build-isolation -v -e .

Then, when C++ files changes:

make -C build install -j $(nproc)

Modified files

Refer to the list of commits in the MR for details.

I separated them in 6 listed below, the first 5 are preparatory commits or complements to the recent merge of pip_release branch:

• [Setup] Remove useless copy of version.txt in python package: not necessary anymore as the python version is managed by setuptools_scm
• [CMake] Minor update for comment location: no functionnal change
• [Setup] Allow empty AIDGE_BUILD_GEN type: allow for specifying AIDGE_BUILD_GEN= (empty) to fall back to default
• [Setup] Remove additional build dependency on toml: prefer to limit the number of dependencies at most for setup.py
• [CMake] Add installation of python binding: responsibility of python bindings lib installation is now in the build system
• [Setup] Add support for editable mode: redirect installation locally in editable mode and document in README.md

Tests

Tested with:

• normal mode on python 3.9
• normal model on python 3.12
• development mode on python 3.9
• development model on python 3.12
• normal mode on windows 3.12
• development mode on windows 3.12
• expected to fail: on windows: setting the Ninja backend fails, no compiler found

TODO / To be discussed

• ninja dependency: Yes, available as a python package ninja. Let optional for the developper.
• symlinks. Removed necessity to have symlinks has the build system installs the library itself
• version.txt. Since changes in packaing, no need to copy version.txt anymore

setup.py

@@ -41,27 +41,23 @@ class CMakeBuild(build_ext):
 
         os.chdir(str(build_temp))
 
-        compile_type = (
-            "Release"
-            if "AIDGE_PYTHON_BUILD_TYPE" not in os.environ
-            else os.environ["AIDGE_PYTHON_BUILD_TYPE"]
-        )
+        compile_type = os.environ.get("AIDGE_PYTHON_BUILD_TYPE", "Release")
         install_path = (
             os.path.join(sys.prefix, "lib", "libAidge")
             if "AIDGE_INSTALL" not in os.environ
             else os.environ["AIDGE_INSTALL"]
         )
-
-        build_gen = (
-            ["-G", os.environ["AIDGE_BUILD_GEN"]]
-            if "AIDGE_BUILD_GEN" in os.environ
+        build_gen = os.environ.get("AIDGE_BUILD_GEN", "")
+        build_gen_opts = (
+            ["-G", build_gen]
+            if build_gen
             else []
         )
 
         self.spawn(
             [
                 "cmake",
-                *build_gen,
+                *build_gen_opts,
                 str(cwd),
                 "-DTEST=OFF",
                 f"-DCMAKE_INSTALL_PREFIX:PATH={install_path}",