30: add nanobind struct example, other refactoring

.gitignore

@@ -2,4 +2,10 @@ _site/
 .jekyll-cache/
 
 .DS_Store
-~$*
+~$*
+
+__pycache__/
+.vscode/
+*.o
+*.so
+build/

30_CCQ/main.md

@@ -72,15 +72,15 @@ nanobind-example/
 ├── CMakeLists.txt
 ├── pyproject.toml
 └── src
-    └── examplepkg
+    └── example_pkg
         ├── compute.py
-        ├── examplemod.cpp
+        ├── array_example_module.cpp
         └── __init__.py
 ```
 
 ---
 
-## nanobind `examplemod.cpp`
+## nanobind `array_example_module.cpp`
 ```c++
 template <typename Scalar>
 void double_arr(
@@ -95,7 +95,7 @@ void double_arr(
     }
 }
 
-NB_MODULE(examplemod, m) {
+NB_MODULE(array_example_module, m) {
     m.def("double_arr", &double_arr<float>);
     m.def("double_arr", &double_arr<double>);
 }
@@ -105,17 +105,17 @@ NB_MODULE(examplemod, m) {
 
 ## nanobind `compute.py`
 ```python
-from . import examplemod
+from . import array_example_module
 
 inarr = np.arange(20)
 outarr = np.empty_like(inarr)
 
-examplemod.double_arr(outarr, inarr)
+array_example_module.double_arr(outarr, inarr)
 ```
 
 - Easy! nanobind will check that the array types have the expected shape, dtype, strides, etc.
 - A more sophisticated example would have nanobind returning a NumPy array
-- Now we'll look at how `examplemod.cpp` gets built
+- Now we'll look at how `array_example_module.cpp` gets built
 
 ---
 
@@ -127,9 +127,9 @@ project(${SKBUILD_PROJECT_NAME} LANGUAGES CXX)
 find_package(Python 3.8 COMPONENTS Interpreter Development.Module REQUIRED)
 find_package(nanobind CONFIG REQUIRED)
 
-nanobind_add_module(examplemod src/examplepkg/examplemod.cpp)
+nanobind_add_module(array_example_module src/example_pkg/array_example_module.cpp)
 
-install(TARGETS examplemod LIBRARY DESTINATION examplepkg)
+install(TARGETS array_example_module LIBRARY DESTINATION example_pkg)
 ```
 
 ---
@@ -141,7 +141,7 @@ requires = ["scikit-build-core >= 0.5", "nanobind"]
 build-backend = "scikit_build_core.build"
 
 [project]
-name = "examplepkg"
+name = "example_pkg"
 version = "0.0.1"
 requires-python = ">=3.8"
 

30_CCQ/nanobind-example/CMakeLists.txt

@@ -4,6 +4,8 @@ project(${SKBUILD_PROJECT_NAME} LANGUAGES CXX)
 find_package(Python 3.8 COMPONENTS Interpreter Development.Module REQUIRED)
 find_package(nanobind CONFIG REQUIRED)
 
-nanobind_add_module(examplemod src/examplepkg/examplemod.cpp)
+nanobind_add_module(array_example_module src/example_pkg/array_example_module.cpp)
+nanobind_add_module(struct_example_module src/example_pkg/struct_example_module.cpp)
 
-install(TARGETS examplemod LIBRARY DESTINATION examplepkg)
+install(TARGETS array_example_module LIBRARY DESTINATION example_pkg)
+install(TARGETS struct_example_module LIBRARY DESTINATION example_pkg)

30_CCQ/nanobind-example/README.md

@@ -15,5 +15,5 @@ $ pip install -e . --no-build-isolation
 
 ## Test
 ```
-$ python -m examplepkg.compute
+$ python -m example_pkg.compute
 ```

30_CCQ/nanobind-example/pyproject.toml

@@ -3,7 +3,7 @@ requires = ["scikit-build-core >= 0.5", "nanobind"]
 build-backend = "scikit_build_core.build"
 
 [project]
-name = "examplepkg"
+name = "example_pkg"
 version = "0.0.1"
 requires-python = ">=3.8"
 

30_CCQ/nanobind-example/src/examplepkg/examplemod.cpp → 30_CCQ/nanobind-example/src/example_pkg/array_example_module.cpp

@@ -15,8 +15,7 @@ void double_arr(nb::ndarray<Scalar, nb::ndim<1>, nb::device::cpu> outarr,
     }
 }
 
-
-NB_MODULE(examplemod, m) {
+NB_MODULE(array_example_module, m) {
     m.def("double_arr", &double_arr<float>);
     m.def("double_arr", &double_arr<double>);
     m.def("double_arr", &double_arr<int64_t>);

30_CCQ/nanobind-example/src/examplepkg/compute.py → 30_CCQ/nanobind-example/src/example_pkg/compute.py

@@ -1,14 +1,12 @@
-from timeit import default_timer
-
 import numpy as np
 
-from . import examplemod
+from . import array_example_module
 
 def main():
     inarr = np.arange(20)
     outarr = np.empty_like(inarr)
 
-    examplemod.double_arr(outarr, inarr)
+    array_example_module.double_arr(outarr, inarr)
 
     print(inarr)
     print(outarr)

30_CCQ/nanobind-example/src/example_pkg/struct_example_module.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+#include <sstream>
+
+#include <nanobind/nanobind.h>
+#include <nanobind/ndarray.h>
+#include <nanobind/stl/string.h>
+
+namespace nb = nanobind;
+
+struct S {
+  int i;
+  S(int i):i{i}{}
+  int m() const { return i+2;}
+};
+
+// A function using S
+int f(S const & s){ return s.i;}
+
+// make S printable in C++
+std::ostream & operator<<(std::ostream &out, S const & s) {
+     return out << "S struct with i=" << s.i << '\n';
+}
+
+NB_MODULE(struct_example_module, m) {
+    nb::class_<S>(m, "S")
+        .def_rw("i", &S::i)
+        .def(nb::init<int>())
+        .def("m", &S::m)
+        .def("__repr__", [](const S& s) {
+          std::stringstream stream;
+          stream << s;
+          return stream.str();
+        });
+    m.def("f", &f);
+}

30_CCQ/nanobind-example/src/example_pkg/test_struct.py

@@ -0,0 +1,13 @@
+from . import struct_example_module
+
+def main():
+    s = struct_example_module.S(3)
+    print()
+    print(f'{s = }')
+    print(f'{s.i = }')
+    print(f'{s.m() = }')
+    print(f'{struct_example_module.f(s) = }')
+    print()
+
+if __name__ == '__main__':
+    main()