add a real module with a preliminary API

Author: mattip

.gitignore

@@ -4,5 +4,15 @@ builds/
 *.pyc
 *.swp
 test.exe
-local/
 dist/
+build/
+libs/
+# These are artifacts when using editable builds
+local/lib
+local/include
+local/openblas.egg-info
+local/openblas/lib
+local/openblas/include
+local/openblas/*.so
+local/openblas/*.pyd
+local/openblas/*.dylib

local/openblas/__init__.py

@@ -0,0 +1,27 @@
+import os
+from . import _init_openblas
+
+# Use importlib.metadata to single-source the version
+
+try:
+    # importlib.metadata is present in Python 3.8 and later
+    import importlib.metadata as importlib_metadata
+except ImportError:
+    # use the shim package importlib-metadata pre-3.8
+    import importlib_metadata as importlib_metadata
+
+try:
+    # __package__ allows for the case where __name__ is "__main__"
+    __version__ = importlib_metadata.version(__package__ or __name__)
+except importlib_metadata.PackageNotFoundError:
+    __version__ = "0.0.0"
+
+openblas_config = _init_openblas.get_config()
+
+path_to_so = os.path.join(os.path.dirname(__file__), 'lib', 'libopenblas64_.so')
+
+
+def open_so():
+    _init_openblas.open_so(path_to_so)
+
+

local/openblas/__main__.py

@@ -0,0 +1,4 @@
+import openblas
+
+if __name__ == "__main__":
+    print(f"OpenBLAS using '{openblas.openblas_config}'")

pyproject.toml

@@ -31,6 +31,9 @@ upstream = "https://github.com/xianyi/OpenBLAS"
 namespaces = true
 where = ["local"]
 
+[options]
+install_requires = "importlib-metadata ~= 1.0 ; python_version < '3.8'"
+
 [tool.setuptools.package-data]
 openblas = ["lib/*", "include/*", "lib/pkgconfig/*", "lib/cmake/openblas/*"]
 

setup.py

@@ -1,4 +1,23 @@
-from setuptools import setup, find_packages
+import os
+from setuptools import setup, Extension
+
+mydir = os.path.abspath(os.path.dirname(__file__))
+
+# TODO: determine if we are building 64- or 32- bit interfaces
+use_64=True
+if use_64:
+    libraries = ["openblas64_",]
+    macros = [("SUFFIX", "64_")]
+else:
+    libraries = ["openblas",]
+    macros = []
 
 setup(
+    ext_modules=[Extension(
+            "openblas._init_openblas", ["src/_init_openblas.c"],
+            libraries=libraries,
+            library_dirs=[os.path.join(mydir, 'local', 'openblas', 'lib'),],
+            extra_link_args=["-Wl,-rpath,$ORIGIN/lib"],
+            define_macros=macros,
+    )],
 )

src/_init_openblas.c

@@ -0,0 +1,58 @@
+#include "Python.h"
+#include <dlfcn.h>
+#include <stdio.h>
+
+#ifdef SUFFIX
+  #define openblas_get_config openblas_get_config64_
+#endif
+
+extern const char * openblas_get_config();
+
+PyObject *
+get_config(PyObject *self, PyObject *args) {
+    const char * config = openblas_get_config();
+    return PyUnicode_FromString(config);
+}
+
+PyObject*
+open_so(PyObject *self, PyObject *args) {
+    const char *utf8 = PyUnicode_AsUTF8(args);
+    if (utf8 == NULL) {
+        return NULL;
+    }
+    void *handle = dlopen(utf8, RTLD_GLOBAL | RTLD_NOW);
+    if (handle == NULL) {
+        PyErr_SetString(PyExc_ValueError, "Could not open SO");
+        return NULL;
+    }
+    Py_RETURN_TRUE; 
+}
+
+static PyMethodDef InitMethods[] = {
+    {"get_config",  get_config, METH_NOARGS,
+     "Return openblas_get_config(), see https://github.com/xianyi/OpenBLAS/wiki/OpenBLAS-Extensions"},
+    {"open_so", open_so, METH_O,
+     "Use dlopen to load the shared object, which must exist"},
+    {NULL, NULL, 0, NULL}        /* Sentinel */
+};
+
+static struct PyModuleDef initmodule = {
+    PyModuleDef_HEAD_INIT,
+    "_init_openblas",   /* name of module */
+    NULL, /* module documentation, may be NULL */
+    -1,       /* size of per-interpreter state of the module,
+                 or -1 if the module keeps state in global variables. */
+    InitMethods
+};
+
+PyMODINIT_FUNC
+PyInit__init_openblas(void)
+{
+    PyObject *m;
+
+    m = PyModule_Create(&initmodule);
+    if (m == NULL)
+        return NULL;
+
+    return m;
+}