Improve CMake extension builder in setup.py

- Better conform to build_ext directory structure
- Select build type according to build_ext '-g' flag
- Check for CMake >= 3.1 on Windows

.appveyor.yml

@@ -10,6 +10,6 @@ install:
 - cmd: git submodule update -q --init --recursive
 build_script:
 - cmd: python setup.py sdist
-- cmd: pip install dist\cmake_example-0.0.1.zip
+- cmd: pip install --verbose dist\cmake_example-0.0.1.zip
 test_script:
 - cmd: python tests\test.py

.travis.yml

@@ -24,6 +24,6 @@ before_install:
 - source venv/bin/activate
 install:
 - python setup.py sdist
-- pip install dist/*.tar.gz
+- pip install --verbose dist/*.tar.gz
 script:
 - python tests/test.py

setup.py

@@ -1,47 +1,57 @@
 import os
+import re
 import sys
 import platform
 import subprocess
 
 from setuptools import setup, Extension
 from setuptools.command.build_ext import build_ext
-from distutils.spawn import find_executable
+from distutils.version import LooseVersion
 
 
 class CMakeExtension(Extension):
     def __init__(self, name, sourcedir=''):
         Extension.__init__(self, name, sources=[])
-        self.sourcedir = sourcedir
+        self.sourcedir = os.path.abspath(sourcedir)
 
 
 class CMakeBuild(build_ext):
     def run(self):
-        if find_executable('cmake') is None:
-            print("CMake must be installed to build this extension")
-            sys.exit(-1)
+        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:
-            build_dir = os.path.join(os.path.dirname(__file__), 'build', 'cmake')
-            if not os.path.exists(build_dir):
-                os.makedirs(build_dir)
-            cmake_dir = os.path.abspath(ext.sourcedir)
+            self.build_extension(ext)
 
-            extpath = self.get_ext_fullpath(ext.name)
-            extfulldir = os.path.abspath(os.path.dirname(extpath))
-            cmake_args = ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=' + extfulldir,
-                          '-DPYTHON_EXECUTABLE=' + sys.executable]
-            build_args = ['--config', 'Release']
+    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]
 
-            if platform.system() == "Windows":
-                cmake_args += ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY_RELEASE=' + extfulldir]
-                if sys.maxsize > 2**32:
-                    cmake_args += ['-A', 'x64']
-                build_args += ['--', '/m']
-            else:
-                build_args += ['--', '-j2']
+        cfg = 'Debug' if self.debug else 'Release'
+        build_args = ['--config', cfg]
 
-            subprocess.check_call(['cmake', cmake_dir] + cmake_args, cwd=build_dir)
-            subprocess.check_call(['cmake', '--build', '.'] + build_args, cwd=build_dir)
+        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']
+
+        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)
+        subprocess.check_call(['cmake', '--build', '.'] + build_args, cwd=self.build_temp)
 
 setup(
     name='cmake_example',