setup: simplify build system using scikit-build

This commit introduces new dependencies: "scikit-built" and "cmake".

scikit-build is a drop-in replacement to setuptools.setup function
allowing to easily compile and package extensions (C/C++/Cython) by
bridging CMake and setuptools. See http://scikit-build.org

CMake is is an open-source, cross-platform family of tools designed
to build, test and package software. See https://cmake.org

Currently, scikit-build and cmake have to be explicitly (see [1]) installed
on the system. This could be done by simply doing:

  pip install -U scikit-build cmake

Author: jcfr

CMakeLists.txt

@@ -1,4 +1,5 @@
 cmake_minimum_required(VERSION 2.8.12)
+
 project(python_cpp_example)
 
 SET(SOURCE_DIR "src/python_cpp_example")
@@ -14,7 +15,9 @@ SET(TESTS ${SOURCES}
 # Generate a test executable
 include_directories(lib/catch/include)
 add_executable("${PROJECT_NAME}_test" ${TESTS})
+set_target_properties("${PROJECT_NAME}_test" PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/tests/bin)
 
 # Generate python module
 add_subdirectory(lib/pybind11)
-pybind11_add_module(python_cpp_example ${SOURCES} "${SOURCE_DIR}/bindings.cpp")
+pybind11_add_module(python_cpp_example ${SOURCES} "${SOURCE_DIR}/bindings.cpp")
+install(TARGETS python_cpp_example DESTINATION src/python_cpp_example)

setup.py

@@ -1,108 +1,28 @@
 #! /usr/bin/env python3
 
-import os
-import re
-import sys
-import sysconfig
-import platform
-import subprocess
+from __future__ import print_function
+from os import sys, path
 
-from distutils.version import LooseVersion
-from setuptools import setup, Extension, find_packages
-from setuptools.command.build_ext import build_ext
-from setuptools.command.test import test as TestCommand
-from shutil import copyfile, copymode
+try:
+    from skbuild import setup
+except ImportError:
+    print('scikit-build is required to build from source.', file=sys.stderr)
+    print('Please run:', file=sys.stderr)
+    print('', file=sys.stderr)
+    print('  python -m pip install scikit-build')
+    sys.exit(1)
 
-
-class CMakeExtension(Extension):
-    def __init__(self, name, sourcedir=''):
-        Extension.__init__(self, name, sources=[])
-        self.sourcedir = os.path.abspath(sourcedir)
-
-
-class CMakeBuild(build_ext):
-    def run(self):
-        try:
-            out = subprocess.check_output(['cmake', '--version'])
-        except OSError:
-            raise RuntimeError(
-                "CMake must be installed to build the following extensions: " +
-                ", ".join(e.name for e in self.extensions))
-
-        if platform.system() == "Windows":
-            cmake_version = LooseVersion(re.search(r'version\s*([\d.]+)',
-                                         out.decode()).group(1))
-            if cmake_version < '3.1.0':
-                raise RuntimeError("CMake >= 3.1.0 is required on Windows")
-
-        for ext in self.extensions:
-            self.build_extension(ext)
-
-    def build_extension(self, ext):
-        extdir = os.path.abspath(
-            os.path.dirname(self.get_ext_fullpath(ext.name)))
-        cmake_args = ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=' + extdir,
-                      '-DPYTHON_EXECUTABLE=' + sys.executable]
-
-        cfg = 'Debug' if self.debug else 'Release'
-        build_args = ['--config', cfg]
-
-        if platform.system() == "Windows":
-            cmake_args += ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY_{}={}'.format(
-                cfg.upper(),
-                extdir)]
-            if sys.maxsize > 2**32:
-                cmake_args += ['-A', 'x64']
-            build_args += ['--', '/m']
-        else:
-            cmake_args += ['-DCMAKE_BUILD_TYPE=' + cfg]
-            build_args += ['--', '-j2']
-
-        env = os.environ.copy()
-        env['CXXFLAGS'] = '{} -DVERSION_INFO=\\"{}\\"'.format(
-            env.get('CXXFLAGS', ''),
-            self.distribution.get_version())
-        if not os.path.exists(self.build_temp):
-            os.makedirs(self.build_temp)
-        subprocess.check_call(['cmake', ext.sourcedir] + cmake_args,
-                              cwd=self.build_temp, env=env)
-        subprocess.check_call(['cmake', '--build', '.'] + build_args,
-                              cwd=self.build_temp)
-        # Copy *_test file to tests directory
-        test_bin = os.path.join(self.build_temp, 'python_cpp_example_test')
-        self.copy_test_file(test_bin)
-        print()  # Add an empty line for cleaner output
-
-    def copy_test_file(self, src_file):
-        '''
-        Copy ``src_file`` to ``dest_file`` ensuring parent directory exists.
-        By default, message like `creating directory /path/to/package` and
-        `copying directory /src/path/to/package -> path/to/package` are displayed on standard output. Adapted from scikit-build.
-        '''
-        # Create directory if needed
-        dest_dir = os.path.join(os.path.dirname(
-            os.path.abspath(__file__)), 'tests', 'bin')
-        if dest_dir != "" and not os.path.exists(dest_dir):
-            print("creating directory {}".format(dest_dir))
-            os.makedirs(dest_dir)
-
-        # Copy file
-        dest_file = os.path.join(dest_dir, os.path.basename(src_file))
-        print("copying {} -> {}".format(src_file, dest_file))
-        copyfile(src_file, dest_file)
-        copymode(src_file, dest_file)
+from setuptools import find_packages
 
 setup(
     name='python_cpp_example',
-    version='0.2',
+    version='0.3',
     author='Benjamin Jack',
     author_email='[email protected]',
     description='A hybrid Python/C++ test project',
     long_description='',
     packages=find_packages('src'),
     package_dir={'':'src'},
-    ext_modules=[CMakeExtension('python_cpp_example/python_cpp_example')],
-    cmdclass=dict(build_ext=CMakeBuild),
     test_suite='tests',
     zip_safe=False,
 )