Add pip install configuration settings

* To enable debug mode and/or libmeshb
* Close #20

README.md

@@ -12,6 +12,18 @@ Python bindings to [tucanos](https://github.com/tucanos/tucanos.git)
 pip install git+https://github.com/tucanos/pytucanos.git
 ```
 
+To install tucanos in debug mode:
+
+```bash
+pip install -C debug=true git+https://github.com/tucanos/pytucanos.git
+```
+
+To install Tucanos with [libmeshb](https://github.com/LoicMarechal/libMeshb) support:
+
+```bash
+pip install -C meshb=true git+https://github.com/tucanos/pytucanos.git
+```
+
 # Benchmarks
 
 ## `.meshb/.solb` I/O

_custom_build/backend.py

@@ -0,0 +1,29 @@
+# adapted from https://github.com/python-pillow/Pillow/blob/main/_custom_build/backend.py
+# see also https://peps.python.org/pep-0517/#in-tree-build-backends
+import sys
+from setuptools.build_meta import build_wheel
+
+backend_class = build_wheel.__self__.__class__
+
+
+class _CustomBuildMetaBackend(backend_class):
+    def run_setup(self, setup_script="setup.py"):
+        if self.config_settings:
+            print(self.config_settings, file=sys.stderr)
+            flags = []
+            if self.config_settings.get("debug", "false").lower() == "true":
+                flags += ["--debug"]
+            if self.config_settings.get("meshb", "false").lower() == "true":
+                flags += ["--features=meshb"]
+            if flags:
+                sys.argv = sys.argv[:1] + ["build_rust"] + flags + sys.argv[1:]
+        return super().run_setup(setup_script)
+
+    def build_wheel(
+        self, wheel_directory, config_settings=None, metadata_directory=None
+    ):
+        self.config_settings = config_settings
+        return super().build_wheel(wheel_directory, config_settings, metadata_directory)
+
+
+build_wheel = _CustomBuildMetaBackend().build_wheel

pyproject.toml

@@ -1,2 +1,4 @@
 [build-system]
 requires = ["setuptools", "wheel", "setuptools-rust"]
+build-backend = "backend"
+backend-path = ["_custom_build"]

setup.py

@@ -1,7 +1,24 @@
 import setuptools
-from setuptools_rust import Binding, RustExtension
+from setuptools_rust import Binding, RustExtension, build_rust
+import sys
+
+
+class BuildRustCommand(build_rust):
+    user_options = build_rust.user_options + [
+        ("features=", None, "Value for cargo --features")
+    ]
+
+    def initialize_options(self):
+        super().initialize_options()
+        self.features = None
+
+    def finalize_options(self):
+        super().finalize_options()
+        ext = self.distribution.rust_extensions[0]
+        ext.debug = self.debug
+        ext.release = not self.debug
+        ext.features = self.features.split(",")
 
-features = []
 
 setuptools.setup(
     name="pytucanos",
@@ -12,10 +29,9 @@
         RustExtension(
             "pytucanos._pytucanos",
             binding=Binding.PyO3,
-            features=features,
-            debug=False,
         )
     ],
+    cmdclass={"build_rust": BuildRustCommand},
     # rust extensions are not zip safe, just like C-extensions.
     zip_safe=False,
 )