Modeling after Astropy's technique for bundling libraries, the imports are now...

Modeling after Astropy's technique for bundling libraries, the imports are now much cleaner. Thanks @embray. Ref #229.

--HG--
branch : feature/issue-229

pytest.ini

 [pytest]
 addopts=--doctest-modules --ignore release.py --ignore setuptools/lib2to3_ex.py --ignore tests/manual_test.py --ignore tests/shlib_test --doctest-glob=pkg_resources/api_tests.txt --ignore scripts/upload-old-releases-as-zip.py
-norecursedirs=dist build *.egg
+norecursedirs=dist build *.egg setuptools/extern

setuptools/__init__.py

@@ -8,12 +8,7 @@ from distutils.core import Command as _Command
 from distutils.util import convert_path
 from fnmatch import fnmatchcase
 
-try:
-    from setuptools._vendor.six.moves import filterfalse
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    from six.moves import filterfalse
+from setuptools.extern.six.moves import filterfalse
 
 import setuptools.version
 from setuptools.extension import Extension

setuptools/command/bdist_egg.py

@@ -11,12 +11,7 @@ import os
 import marshal
 import textwrap
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from pkg_resources import get_build_platform, Distribution, ensure_directory
 from pkg_resources import EntryPoint

setuptools/command/develop.py

@@ -5,12 +5,7 @@ import os
 import glob
 import io
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from pkg_resources import Distribution, PathMetadata, normalize_path
 from setuptools.command.easy_install import easy_install

setuptools/command/easy_install.py

@@ -40,14 +40,8 @@ import subprocess
 import shlex
 import io
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import configparser
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import configparser
+from setuptools.extern import six
+from setuptools.extern.six.moves import configparser
 
 from setuptools import Command
 from setuptools.sandbox import run_setup

setuptools/command/egg_info.py

@@ -14,12 +14,7 @@ import io
 import warnings
 import time
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from setuptools import Command
 from setuptools.command.sdist import sdist

setuptools/command/rotate.py

@@ -3,12 +3,7 @@ from distutils import log
 from distutils.errors import DistutilsOptionError
 import os
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from setuptools import Command
 

setuptools/command/sdist.py

@@ -5,12 +5,7 @@ import os
 import sys
 import io
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from setuptools.utils import cs_path_exists
 

setuptools/command/setopt.py

@@ -4,12 +4,7 @@ from distutils.errors import DistutilsOptionError
 import distutils
 import os
 
-try:
-    from setuptools._vendor.six.moves import configparser
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    from six.moves import configparser
+from setuptools.extern.six.moves import configparser
 
 from setuptools import Command
 

setuptools/command/test.py

@@ -2,12 +2,7 @@ from distutils.errors import DistutilsOptionError
 from unittest import TestLoader
 import sys
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from pkg_resources import (resource_listdir, resource_exists, normalize_path,
                            working_set, _namespace_packages,

setuptools/command/upload_docs.py

@@ -16,14 +16,8 @@ import tempfile
 import sys
 import shutil
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import http_client, urllib
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import http_client, urllib
+from setuptools.extern import six
+from setuptools.extern.six.moves import http_client, urllib
 
 from pkg_resources import iter_entry_points
 

setuptools/depends.py

@@ -4,12 +4,7 @@ import marshal
 from imp import PKG_DIRECTORY, PY_COMPILED, PY_SOURCE, PY_FROZEN
 from distutils.version import StrictVersion
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 __all__ = [
     'Require', 'find_module', 'get_module_constant', 'extract_constant'

setuptools/dist.py

@@ -13,12 +13,7 @@ from distutils.core import Distribution as _Distribution
 from distutils.errors import (DistutilsOptionError, DistutilsPlatformError,
     DistutilsSetupError)
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 from setuptools.depends import Require
 from setuptools import windows_support

setuptools/extern/six.py

+"""
+Handle loading six package from system or from the bundled copy
+"""
+
+import imp
+
+
+_SIX_SEARCH_PATH = ['setuptools._vendor.six', 'six']
+
+
+def _find_module(name, path=None):
+    """
+    Alternative to `imp.find_module` that can also search in subpackages.
+    """
+
+    parts = name.split('.')
+
+    for part in parts:
+        if path is not None:
+            path = [path]
+
+        fh, path, descr = imp.find_module(part, path)
+
+    return fh, path, descr
+
+
+def _import_six(search_path=_SIX_SEARCH_PATH):
+    for mod_name in search_path:
+        try:
+            mod_info = _find_module(mod_name)
+        except ImportError:
+            continue
+
+        imp.load_module(__name__, *mod_info)
+
+        break
+
+    else:
+        raise ImportError(
+            "The 'six' module of minimum version {0} is required; "
+            "normally this is bundled with this package so if you get "
+            "this warning, consult the packager of your "
+            "distribution.")
+
+
+_import_six()

setuptools/package_index.py

@@ -14,14 +14,8 @@ try:
 except ImportError:
     from urllib2 import splituser
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import urllib, http_client, configparser
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import urllib, http_client, configparser
+from setuptools.extern import six
+from setuptools.extern.six.moves import urllib, http_client, configparser
 
 from pkg_resources import (
     CHECKOUT_DIST, Distribution, BINARY_DIST, normalize_path, SOURCE_DIST,

setuptools/sandbox.py

@@ -8,14 +8,8 @@ import re
 import contextlib
 import pickle
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import builtins
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import builtins
+from setuptools.extern import six
+from setuptools.extern.six.moves import builtins
 
 import pkg_resources
 

setuptools/ssl_support.py

@@ -3,12 +3,7 @@ import socket
 import atexit
 import re
 
-try:
-    from setuptools._vendor.six.moves import urllib, http_client
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    from six.moves import urllib, http_client
+from setuptools.extern.six.moves import urllib, http_client
 
 import pkg_resources
 from pkg_resources import ResolutionError, ExtractionError

setuptools/tests/__init__.py

@@ -8,12 +8,7 @@ from distutils.errors import DistutilsSetupError
 from distutils.core import Extension
 from distutils.version import LooseVersion
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 import pytest
 
 import setuptools.dist

setuptools/tests/contexts.py

@@ -5,12 +5,7 @@ import sys
 import contextlib
 import site
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 
 @contextlib.contextmanager

setuptools/tests/server.py

@@ -4,12 +4,7 @@
 import time
 import threading
 
-try:
-    from setuptools._vendor.six.moves import BaseHTTPServer, SimpleHTTPServer
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    from six.moves import BaseHTTPServer, SimpleHTTPServer
+from setuptools.extern.six.moves import BaseHTTPServer, SimpleHTTPServer
 
 
 class IndexServer(BaseHTTPServer.HTTPServer):

setuptools/tests/test_develop.py

@@ -5,12 +5,7 @@ import site
 import sys
 import io
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 import pytest
 

setuptools/tests/test_easy_install.py

@@ -16,14 +16,8 @@ import itertools
 import distutils.errors
 import io
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import urllib
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import urllib
+from setuptools.extern import six
+from setuptools.extern.six.moves import urllib
 
 import pytest
 try:

setuptools/tests/test_integration.py

@@ -7,14 +7,7 @@ import glob
 import os
 import sys
 
-try:
-    from setuptools._vendor.six.moves import urllib
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    from six.moves import urllib
-
-
+from setuptools.extern.six.moves import urllib
 import pytest
 
 from setuptools.command.easy_install import easy_install

setuptools/tests/test_packageindex.py

@@ -4,14 +4,8 @@ import sys
 import os
 import distutils.errors
 
-try:
-    from setuptools._vendor import six
-    from setuptools._vendor.six.moves import urllib, http_client
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
-    from six.moves import urllib, http_client
+from setuptools.extern import six
+from setuptools.extern.six.moves import urllib, http_client
 
 from .textwrap import DALS
 import pkg_resources

setuptools/tests/test_sdist.py

@@ -9,12 +9,7 @@ import unicodedata
 import contextlib
 import io
 
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 import pytest
 

setuptools/unicode_utils.py

 import unicodedata
 import sys
 
-
-try:
-    from setuptools._vendor import six
-except ImportError:
-    # fallback to naturally-installed version; allows system packagers to
-    #  omit vendored packages.
-    import six
+from setuptools.extern import six
 
 # HFS Plus uses decomposed UTF-8
 def decompose(path):