- Adjusted ``setup.py`` file to support the possible future

removal of the ``setuptools.Feature`` extension from setuptools.
If this keyword isn't present, the setup will still succeed
with setuptools rather than falling back to distutils.  C extension
building can be disabled now also by setting the
DISABLE_SQLALCHEMY_CEXT environment variable.  This variable works
whether or not setuptools is even available. fixes #2986
- using platform.python_implementation() in setup.py to detect CPython.
I've tested this function on OSX and linux on Python 2.6 through 3.4,
including 3.1, 3.2, 3.3.
Unfortunately, on OSX + 3.2 only, it seems to segfault.  I've tried
installing 3.2.5 from the python.org .dmg, building it from source,
and also blew away the whole 3.2 directory, something seems to be wrong
with the "platform" module on that platform only, and there's also no
issue on bugs.python.org; however, I'm going with
it anyway. If someone is using 3.2 on OSX they really should be upgrading.

1 files changed, 31 insertions, 9 deletions

diff --git a/setup.py b/setup.py
index f682081df..298dc8bb4 100644
--- a/setup.py
+++ b/setup.py
@@ -10,18 +10,33 @@ import sys
 from distutils.command.build_ext import build_ext
 from distutils.errors import (CCompilerError, DistutilsExecError,
                               DistutilsPlatformError)
+
+has_feature = False
 try:
-    from setuptools import setup, Extension, Feature
-    has_setuptools = True
+    from setuptools import setup, Extension
+    try:
+        # see
+        # https://bitbucket.org/pypa/setuptools/issue/65/deprecate-and-remove-features,
+        # where they may remove Feature.
+        from setuptools import Feature
+        has_feature = True
+    except ImportError:
+        pass
 except ImportError:
-    has_setuptools = False
     from distutils.core import setup, Extension
-    Feature = None
 
-cmdclass = {}
-pypy = hasattr(sys, 'pypy_version_info')
-jython = sys.platform.startswith('java')
+try:
+    import platform
+except ImportError:
+    pypy = hasattr(sys, 'pypy_version_info')
+    jython = sys.platform.startswith('java')
+    cpython = not pypy and not jython
+else:
+    cpython = platform.python_implementation() == 'CPython'
+
 py3k = False
+
+cmdclass = {}
 extra = {}
 if sys.version_info < (2, 6):
     raise Exception("SQLAlchemy requires Python 2.6 or higher.")
@@ -100,7 +115,7 @@ r_file.close()
 def run_setup(with_cext):
     kwargs = extra.copy()
     if with_cext:
-        if Feature:
+        if has_feature:
             kwargs['features'] = {'cextensions': Feature(
                     "optional C speed-enhancements",
                     standard=True,
@@ -137,13 +152,20 @@ def run_setup(with_cext):
             **kwargs
           )
 
-if pypy or jython:
+if not cpython:
     run_setup(False)
     status_msgs(
         "WARNING: C extensions are not supported on " +
             "this Python platform, speedups are not enabled.",
         "Plain-Python build succeeded."
     )
+elif os.environ.get('DISABLE_SQLALCHEMY_CEXT'):
+    run_setup(False)
+    status_msgs(
+        "DISABLE_SQLALCHEMY_CEXT is set; not attempting to build C extensions.",
+        "Plain-Python build succeeded."
+    )
+
 else:
     try:
         run_setup(True)