Respect PURE_PYTHON at runtime. Partial fix for #33.issue33a

2 files changed, 18 insertions, 9 deletions

diff --git a/src/zope/security/checker.py b/src/zope/security/checker.py
index d617ef4..238f748 100644
--- a/src/zope/security/checker.py
+++ b/src/zope/security/checker.py
@@ -49,6 +49,7 @@ from zope.security.interfaces import Unauthorized
 from zope.security._definitions import thread_local
 from zope.security._compat import CLASS_TYPES
 from zope.security._compat import PYTHON2
+from zope.security._compat import PURE_PYTHON
 from zope.security.proxy import Proxy
 from zope.security.proxy import getChecker
 
@@ -438,11 +439,14 @@ _defaultChecker = Checker({})
 _available_by_default = []
 
 # Get optimized versions
-try:
-    import zope.security._zope_security_checker
-except (ImportError, AttributeError): #pragma NO COVER PyPy / PURE_PYTHON
-    pass
-else:
+_c_available = not PURE_PYTHON
+if _c_available:
+    try:
+        import zope.security._zope_security_checker
+    except (ImportError, AttributeError): #pragma NO COVER PyPy / PURE_PYTHON
+        _c_available = False
+
+if _c_available:
     from zope.security._zope_security_checker import _checkers, selectChecker
     from zope.security._zope_security_checker import NoProxy, Checker
     from zope.security._zope_security_checker import _defaultChecker
diff --git a/src/zope/security/proxy.py b/src/zope/security/proxy.py
index 60dcae8..9e7333d 100644
--- a/src/zope/security/proxy.py
+++ b/src/zope/security/proxy.py
@@ -17,7 +17,7 @@ import functools
 import sys
 
 from zope.proxy import PyProxyBase
-from zope.security._compat import PYPY
+from zope.security._compat import PYPY, PURE_PYTHON
 from zope.security.interfaces import ForbiddenAttribute
 
 def _check_name(meth, wrap_result=True):
@@ -346,9 +346,14 @@ def getObjectPy(proxy):
         return proxy
     return super(PyProxyBase, proxy).__getattribute__('_wrapped')
 
-try:
-    from zope.security._proxy import _Proxy
-except (ImportError, AttributeError): #pragma NO COVER PyPy / PURE_PYTHON
+_c_available = not PURE_PYTHON
+if _c_available:
+    try:
+        from zope.security._proxy import _Proxy
+    except (ImportError, AttributeError): #pragma NO COVER PyPy / PURE_PYTHON
+        _c_available = False
+
+if not _c_available:
     getChecker = getCheckerPy
     getObject = getObjectPy
     Proxy = ProxyPy