Noramlize 'setup.py' to fit conventions:

- Comply with flake8, except for indentation width, which is 2.

- Move human-centric metadata to top of 'setup()' call.

- Add Trove classifiers for supported Python versions.

- Use 'find_packages()' + MANIFEST.in to avoid errors in listing
  modules and packages.

Closes #131 and #161.

python/MANIFEST.in

@@ -0,0 +1,14 @@
+prune google/protobuf/internal/import_test_package
+exclude google/protobuf/internal/*_pb2.py
+exclude google/protobuf/internal/*_test.py
+exclude google/protobuf/internal/*.proto
+exclude google/protobuf/internal/test_util.py
+
+recursive-exclude google *_test.py
+recursive-exclude google *_test.proto
+recursive-exclude google unittest*_pb2.py
+
+global-exclude *.dll
+global-exclude *.pyc
+global-exclude *.pyo
+global-exclude *.so

python/setup.py

@@ -8,28 +8,29 @@ import subprocess
 # We must use setuptools, not distutils, because we need to use the
 # namespace_packages option for the "google" package.
 try:
-  from setuptools import setup, Extension
+  from setuptools import setup, Extension, find_packages
 except ImportError:
   try:
     from ez_setup import use_setuptools
     use_setuptools()
-    from setuptools import setup, Extension
+    from setuptools import setup, Extension, find_packages
   except ImportError:
     sys.stderr.write(
         "Could not import setuptools; make sure you have setuptools or "
-        "ez_setup installed.\n")
+        "ez_setup installed.\n"
+    )
     raise
+
 from distutils.command.clean import clean as _clean
-if sys.version_info[0] >= 3:
-    # Python 3
-    from distutils.command.build_py import build_py_2to3 as _build_py
+
+if sys.version_info[0] == 3:
+  # Python 3
+  from distutils.command.build_py import build_py_2to3 as _build_py
 else:
-    # Python 2
-    from distutils.command.build_py import build_py as _build_py
+  # Python 2
+  from distutils.command.build_py import build_py as _build_py
 from distutils.spawn import find_executable
 
-maintainer_email = "protobuf@googlegroups.com"
-
 # Find the Protocol Compiler.
 if 'PROTOC' in os.environ and os.path.exists(os.environ['PROTOC']):
   protoc = os.environ['PROTOC']
@@ -44,13 +45,13 @@ elif os.path.exists("../vsprojects/Release/protoc.exe"):
 else:
   protoc = find_executable("protoc")
 
+
 def GetVersion():
   """Gets the version from google/protobuf/__init__.py
 
-  Do not import google.protobuf.__init__ directly, because an installed protobuf
-  library may be loaded instead.
+  Do not import google.protobuf.__init__ directly, because an installed
+  protobuf library may be loaded instead."""
 
-  """
   with open(os.path.join('google', 'protobuf', '__init__.py')) as version_file:
     exec(version_file.read())
     return __version__
@@ -66,22 +67,24 @@ def generate_proto(source):
   if (not os.path.exists(output) or
       (os.path.exists(source) and
        os.path.getmtime(source) > os.path.getmtime(output))):
-    print ("Generating %s..." % output)
+    print("Generating %s..." % output)
 
     if not os.path.exists(source):
       sys.stderr.write("Can't find required file: %s\n" % source)
       sys.exit(-1)
 
-    if protoc == None:
+    if protoc is None:
       sys.stderr.write(
-          "protoc is not installed nor found in ../src.  Please compile it "
-          "or install the binary package.\n")
+          "protoc is not installed nor found in ../src. "
+          "Please compile it or install the binary package.\n"
+      )
       sys.exit(-1)
 
-    protoc_command = [ protoc, "-I../src", "-I.", "--python_out=.", source ]
+    protoc_command = [protoc, "-I../src", "-I.", "--python_out=.", source]
     if subprocess.call(protoc_command) != 0:
       sys.exit(-1)
 
+
 def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/unittest.proto")
   generate_proto("../src/google/protobuf/unittest_custom_options.proto")
@@ -92,17 +95,18 @@ def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/unittest_proto3_arena.proto")
   generate_proto("google/protobuf/internal/descriptor_pool_test1.proto")
   generate_proto("google/protobuf/internal/descriptor_pool_test2.proto")
-  generate_proto("google/protobuf/internal/test_bad_identifiers.proto")
-  generate_proto("google/protobuf/internal/missing_enum_values.proto")
-  generate_proto("google/protobuf/internal/more_extensions.proto")
-  generate_proto("google/protobuf/internal/more_extensions_dynamic.proto")
-  generate_proto("google/protobuf/internal/more_messages.proto")
   generate_proto("google/protobuf/internal/factory_test1.proto")
   generate_proto("google/protobuf/internal/factory_test2.proto")
   generate_proto("google/protobuf/internal/import_test_package/inner.proto")
   generate_proto("google/protobuf/internal/import_test_package/outer.proto")
+  generate_proto("google/protobuf/internal/missing_enum_values.proto")
+  generate_proto("google/protobuf/internal/more_extensions.proto")
+  generate_proto("google/protobuf/internal/more_extensions_dynamic.proto")
+  generate_proto("google/protobuf/internal/more_messages.proto")
+  generate_proto("google/protobuf/internal/test_bad_identifiers.proto")
   generate_proto("google/protobuf/pyext/python.proto")
 
+
 class clean(_clean):
   def run(self):
     # Delete generated files in the code tree.
@@ -110,12 +114,13 @@ class clean(_clean):
       for filename in filenames:
         filepath = os.path.join(dirpath, filename)
         if filepath.endswith("_pb2.py") or filepath.endswith(".pyc") or \
-          filepath.endswith(".so") or filepath.endswith(".o") or \
-          filepath.endswith('google/protobuf/compiler/__init__.py'):
+           filepath.endswith(".so") or filepath.endswith(".o") or \
+           filepath.endswith('google/protobuf/compiler/__init__.py'):
           os.remove(filepath)
     # _clean is an old-style class, so super() doesn't work.
     _clean.run(self)
 
+
 class build_py(_build_py):
   def run(self):
     # Generate necessary .proto file if it doesn't exist.
@@ -132,11 +137,11 @@ class build_py(_build_py):
     # _build_py is an old-style class, so super() doesn't work.
     _build_py.run(self)
   # TODO(mrovner): Subclass to run 2to3 on some files only.
-  # Tracing what https://wiki.python.org/moin/PortingPythonToPy3k's "Approach 2"
-  # section on how to get 2to3 to run on source files during install under
-  # Python 3.  This class seems like a good place to put logic that calls
-  # python3's distutils.util.run_2to3 on the subset of the files we have in our
-  # release that are subject to conversion.
+  # Tracing what https://wiki.python.org/moin/PortingPythonToPy3k's
+  # "Approach 2" section on how to get 2to3 to run on source files during
+  # install under Python 3.  This class seems like a good place to put logic
+  # that calls python3's distutils.util.run_2to3 on the subset of the files we
+  # have in our release that are subject to conversion.
   # See code reference in previous code review.
 
 if __name__ == '__main__':
@@ -145,61 +150,49 @@ if __name__ == '__main__':
   if cpp_impl in sys.argv:
     sys.argv.remove(cpp_impl)
     # C++ implementation extension
-    ext_module_list.append(Extension(
-        "google.protobuf.pyext._message",
-        [ "google/protobuf/pyext/descriptor.cc",
-          "google/protobuf/pyext/descriptor_containers.cc",
-          "google/protobuf/pyext/descriptor_pool.cc",
-          "google/protobuf/pyext/message.cc",
-          "google/protobuf/pyext/extension_dict.cc",
-          "google/protobuf/pyext/repeated_scalar_container.cc",
-          "google/protobuf/pyext/repeated_composite_container.cc" ],
-        define_macros=[('GOOGLE_PROTOBUF_HAS_ONEOF', '1')],
-        include_dirs = [ ".", "../src" ],
-        libraries = [ "protobuf" ],
-        library_dirs = [ '../src/.libs' ],
-        ))
+    ext_module_list.append(
+        Extension(
+            "google.protobuf.pyext._message",
+            [
+                "google/protobuf/pyext/descriptor.cc",
+                "google/protobuf/pyext/descriptor_containers.cc",
+                "google/protobuf/pyext/descriptor_pool.cc",
+                "google/protobuf/pyext/extension_dict.cc",
+                "google/protobuf/pyext/message.cc",
+                "google/protobuf/pyext/repeated_composite_container.cc",
+                "google/protobuf/pyext/repeated_scalar_container.cc",
+            ],
+            define_macros=[('GOOGLE_PROTOBUF_HAS_ONEOF', '1')],
+            include_dirs=[".", "../src"],
+            libraries=['protobuf'],
+            library_dirs=['../src/.libs'],
+        )
+    )
     os.environ['PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'] = 'cpp'
 
-  setup(name = 'protobuf',
-        version = GetVersion(),
-        packages = [ 'google' ],
-        namespace_packages = [ 'google' ],
-        test_suite = 'google.protobuf.internal',
-        # Must list modules explicitly so that we don't install tests.
-        py_modules = [
-          'google.protobuf.internal.api_implementation',
-          'google.protobuf.internal.containers',
-          'google.protobuf.internal.decoder',
-          'google.protobuf.internal.encoder',
-          'google.protobuf.internal.enum_type_wrapper',
-          'google.protobuf.internal.message_listener',
-          'google.protobuf.internal.python_message',
-          'google.protobuf.internal.type_checkers',
-          'google.protobuf.internal.wire_format',
-          'google.protobuf.descriptor',
-          'google.protobuf.descriptor_pb2',
-          'google.protobuf.compiler.plugin_pb2',
-          'google.protobuf.message',
-          'google.protobuf.descriptor_database',
-          'google.protobuf.descriptor_pool',
-          'google.protobuf.message_factory',
-          'google.protobuf.proto_builder',
-          'google.protobuf.pyext.cpp_message',
-          'google.protobuf.reflection',
-          'google.protobuf.service',
-          'google.protobuf.service_reflection',
-          'google.protobuf.symbol_database',
-          'google.protobuf.text_encoding',
-          'google.protobuf.text_format'],
-        cmdclass = { 'clean': clean, 'build_py': build_py },
-        install_requires = ['setuptools'],
-        ext_modules = ext_module_list,
-        url = 'https://developers.google.com/protocol-buffers/',
-        maintainer = maintainer_email,
-        maintainer_email = 'protobuf@googlegroups.com',
-        license = 'New BSD License',
-        description = 'Protocol Buffers',
-        long_description =
-          "Protocol Buffers are Google's data interchange format.",
-        )
+  setup(
+      name='protobuf',
+      version=GetVersion(),
+      description='Protocol Buffers',
+      long_description="Protocol Buffers are Google's data interchange format",
+      url='https://developers.google.com/protocol-buffers/',
+      maintainer='protobuf@googlegroups.com',
+      maintainer_email='protobuf@googlegroups.com',
+      license='New BSD License',
+      classifiers=[
+          'Programming Language :: Python :: 2.7',
+      ],
+      namespace_packages=['google'],
+      packages=find_packages(
+          exclude=[
+              'import_test_package',
+          ],
+      ),
+      test_suite='google.protobuf.internal',
+      cmdclass={
+          'clean': clean,
+          'build_py': build_py,
+      },
+      install_requires=['setuptools'],
+      ext_modules=ext_module_list,
+  )