fixes setup.py

setup.py

@@ -10,8 +10,11 @@ from setuptools.command.install import install
 from setuptools.command.develop import develop
 from distutils.version import LooseVersion
 
-# Installation via pip: pip install -e .
-# If GPU backend: pip install -e . --install-option="--GPU"
+"""
+Install python wrapper of virtual fluids
+Install GPU backend with option --GPU
+(pass to pip via --install-option="--GPU")
+"""
 
 vf_cmake_args = [
     "-DBUILD_VF_PYTHON_BINDINGS=ON",
@@ -36,6 +39,7 @@ vf_gpu_cmake_args = [
     "-DBUILD_VF_UNIT_TESTS:BOOL=OFF",
 ]
 
+GPU = False
 
 class CommandMixin:
     user_options = [
@@ -46,12 +50,23 @@ class CommandMixin:
         super().initialize_options()
         self.GPU = False
 
+    def finalize_options(self):
+        super().finalize_options()
+
+    def run(self):
+        global GPU
+        GPU = GPU or self.GPU
+        super().run()
+
+
 class InstallCommand(CommandMixin, install):
     user_options = getattr(install, 'user_options', []) + CommandMixin.user_options
 
+
 class DevelopCommand(CommandMixin, develop):
     user_options = getattr(develop, 'user_options', []) + CommandMixin.user_options
 
+
 class CMakeExtension(Extension):
     def __init__(self, name, sourcedir=''):
         Extension.__init__(self, name, sources=[])
@@ -99,7 +114,7 @@ class CMakeBuild(CommandMixin, build_ext):
             build_args += ['--', '-j2']
 
         cmake_args.extend(vf_cmake_args)
-        cmake_args.extend(vf_gpu_cmake_args if self.GPU else vf_cpu_cmake_args)
+        cmake_args.extend(vf_gpu_cmake_args if GPU else vf_cpu_cmake_args)
 
         env = os.environ.copy()
         env['CXXFLAGS'] = '{} -DVERSION_INFO=\\"{}\\"'.format(env.get('CXXFLAGS', ''),
@@ -117,6 +132,6 @@ setup(
     name='pyfluids',
     version='0.0.1',
     ext_modules=[CMakeExtension('pyfluids')],
-    cmdclass={"install": InstallCommand, "develop": DevelopCommand, "build_ext":CMakeBuild},
+    cmdclass={"install": InstallCommand, "develop": DevelopCommand, "build_ext": CMakeBuild},
     zip_safe=False,
 )