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

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

2 files changed, 46 insertions, 0 deletions

diff --git a/setuptools/extern/__init__.py b/setuptools/extern/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/setuptools/extern/__init__.py
diff --git a/setuptools/extern/six.py b/setuptools/extern/six.py
new file mode 100644
index 00000000..2685c5e6
--- /dev/null
+++ b/setuptools/extern/six.py
@@ -0,0 +1,46 @@
+"""
+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()