[Setup] Add support for development install

Add support for pip -e development (editable) mode.
Add some environment vars for configuring the cmake build in
development mode:
- AIDGE_BUILD_GEN=<cmake_backend>: for instance Ninja to use
  the ninja backend which better supports incremental build
- AIDGE_BUILD_MODE=[Debug|Release]: define the build mode,
  defaults to Debug

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:

export AIDGE_BUILD_GEN=Ninja
pip install --no-build-isolation -v -e .

Refer to the doc string of setup.py for details.

README.md

@@ -19,6 +19,25 @@ pip install . -v
 export AIDGE_INSTALL='<path_to_aidge>/install'
 ```
 
+## Development Mode installation
+
+Install in development mode (local changes to python files and .cpp files do not require full installation)
+with:
+```bash
+pip install cmake ninja # install first build dependencies
+export AIDGE_BUILD_GEN=Ninja
+pip install --no-build-isolation -v -e .
+```
+
+After changes in a python file, no action is required, for changes in .cpp/.h file, re-execute:
+```bash
+pip install --no-build-isolation -v -e .
+```
+
+In this mode, the C++ compilation build system is located in the local `build/` directory.
+
+Refer to the doc string in `setup.py`for more details on editable mode.
+
 ## Standard C++ Compilation
 
 Create two directories ``build`` and ``ìnstall``.

setup.py

 #!/usr/bin/env python3
 """ Aidge
 
+This setup file supports both install and develop (editable) mode, i.e.:
+- either: pip install -v .
+- or editable: pip install [--no-build-isolation] -v -e .
+  (use --no-build-isolation preferably for modern installation, see [1] below)
+
+In editable mode, there is no need to reinstall after changes in the pythons files.
+Also, when changing C++ source files, incremental compilation works and build
+directory is located in build/, though one must re-run after C++ changes, either:
+- reinstall; pip install [--no-build-isolation] -v -e .
+- or cmake: cmake --build build && cmake --install build
+- or direct build command: ninja -C build install / make -C build install
+
+Note that in editable mode, one must first install build dependencies as they
+will not be automatically installed:
+- pip install cmake ninja
+
+[1] on modern setuptools/python versions, isolation mode breaks the incremental
+build due to the reinstall of build tools in different locations,
+use --no-build_isolation to avoid this.
+
 #TODO To change
 POC of the next framework named Aidge
 """
@@ -14,7 +34,6 @@ import os
 if sys.version_info[:2] < (3, 7):
     raise RuntimeError("Python version >= 3.7 required.")
 
-
 CLASSIFIERS = """\
 Development Status :: 2 - Pre-Alpha
 """
@@ -30,12 +49,21 @@ from setuptools import setup, Extension
 from setuptools import find_packages
 from setuptools.command.build_ext import build_ext
 
+SETUP_DIR = pathlib.Path(__file__).parent
+
+def parse_requirements():
+    with open(SETUP_DIR / "requirements.txt", "r") as inf:
+        return [
+            line
+            for line in [l.strip() for l in inf.readlines()]
+            if line
+        ]
+
 def get_project_name() -> str:
-    return open(pathlib.Path().absolute() / "project_name.txt", "r").read()
+    return open(SETUP_DIR / "project_name.txt", "r").read().strip()
 
 def get_project_version() -> str:
-    aidge_root = pathlib.Path().absolute()
-    version = open(aidge_root / "version.txt", "r").read().strip()
+    version = open(SETUP_DIR / "version.txt", "r").read().strip()
     return version
 
 
@@ -45,9 +73,19 @@ class CMakeExtension(Extension):
 
 class CMakeBuild(build_ext):
 
+    def __init__(self, dist, *args, **kwargs):
+        super().__init__(dist, *args, **kwargs)
+        # Detect editable_mode for old versions of setuptools
+        if not hasattr(self, "editable_mode"):
+            if hasattr(dist, "commands"):
+                self.editable_mode = "develop" in dist.commands
+            else:
+                self.editable_mode = False
+
     def run(self):
         # This lists the number of processors available on the machine
         # The compilation will use half of them
+        # Note that for ninja backend this is not necessary
         max_jobs = str(ceil(multiprocessing.cpu_count() / 2))
 
         cwd = pathlib.Path().absolute()
@@ -60,37 +98,39 @@ class CMakeBuild(build_ext):
         if not build_lib.exists():
             build_lib.mkdir(parents=True, exist_ok=True)
 
-        os.chdir(str(build_temp))
-
         # Impose to use the executable of the python
         # used to launch setup.py to setup PythonInterp
         param_py = "-DPYTHON_EXECUTABLE=" + sys.executable
 
-        compile_type = 'Debug'
+        build_gen = os.environ.get("AIDGE_BUILD_GEN", "")
+        cmake_type_opts = ['-G', build_gen] if build_gen else []
+        cmake_job_opts = ['-j', max_jobs] if build_gen != "Ninja" else []
+        compile_type = os.environ.get("AIDGE_BUILD_MODE", "Debug")
         install_path = os.path.join(sys.prefix, "lib", "libAidge")  if "AIDGE_INSTALL" not in os.environ else os.environ["AIDGE_INSTALL"]
 
-        self.spawn(['cmake', str(cwd), param_py, '-DTEST=OFF', f'-DCMAKE_INSTALL_PREFIX:PATH={install_path}', f'-DCMAKE_BUILD_TYPE={compile_type}'])
+        os.chdir(str(build_temp))
+        self.spawn(['cmake', *cmake_type_opts, str(cwd), param_py, '-DTEST=OFF', f'-DCMAKE_INSTALL_PREFIX:PATH={install_path}', f'-DCMAKE_BUILD_TYPE={compile_type}'])
         if not self.dry_run:
-            self.spawn(['cmake', '--build', '.', '--config', compile_type, '-j', max_jobs])
+            self.spawn(['cmake', '--build', '.', '--config', compile_type, *cmake_job_opts])
             self.spawn(['cmake', '--install', '.', '--config', compile_type])
         os.chdir(str(cwd))
 
-        aidge_package = build_lib / (get_project_name())
+        package_path_prefix = build_lib if not self.editable_mode else SETUP_DIR
+        aidge_package = (package_path_prefix / get_project_name()).absolute()
 
         # Get "aidge core" package
         # ext_lib = build_temp
-        print(build_temp.absolute())
         # Copy all shared object files from build_temp/lib to aidge_package
-        for root, _, files in os.walk(build_temp.absolute()):
+        for root, _, files in os.walk(build_temp):
             for file in files:
-                if (file.endswith('.so') or file.endswith('.pyd')) and (root != str(aidge_package.absolute())):
-                    currentFile=os.path.join(root, file)
-                    shutil.copy(currentFile, str(aidge_package.absolute()))
+                if ((file.endswith('.so') or file.endswith('.pyd')) and
+                    root != str(aidge_package) and
+                    not root.startswith(str(build_lib))):
+                    currentFile = pathlib.Path(root) / file
+                    shutil.copy(str(currentFile), str(aidge_package))
 
         # Copy version.txt in aidge_package
-        os.chdir(os.path.dirname(__file__))
-        shutil.copy("version.txt", str(aidge_package.absolute()))
-
+        shutil.copy(str(SETUP_DIR / "version.txt"), str(aidge_package))
 
 if __name__ == '__main__':
 
@@ -105,6 +145,8 @@ if __name__ == '__main__':
         packages=find_packages(where="."),
         include_package_data=True,
         ext_modules=[CMakeExtension(get_project_name())],
+        install_requires=parse_requirements(),
+        setup_requires=['cmake', 'ninja'],
         cmdclass={
             'build_ext': CMakeBuild,
         },