support method slots specific to a Python version

Cython/Compiler/Code.py

@@ -89,6 +89,9 @@ class CCodeWriter:
             self.input_file_contents[file] = F
             return F
 
+    def get_py_version_hex(self, pyversion):
+        return "0x%02X%02X%02X%02X" % (tuple(pyversion) + (0,0,0,0))[:4]
+
     def mark_pos(self, pos):
         file, line, col = pos
         contents = self.file_contents(file)

Cython/Compiler/TypeSlots.py

@@ -104,16 +104,22 @@ class SlotDescriptor:
     #  slot_name    string           Member name of the slot in the type object
     #  is_initialised_dynamically    Is initialised by code in the module init function
 
-    def __init__(self, slot_name, dynamic = 0):
+    def __init__(self, slot_name, dynamic = 0, min_python_version = None):
         self.slot_name = slot_name
         self.is_initialised_dynamically = dynamic
+        self.min_python_version = min_python_version
 
     def generate(self, scope, code):
         if self.is_initialised_dynamically:
             value = 0
         else:
             value = self.slot_code(scope)
+        if self.min_python_version is not None:
+            code.putln("#if PY_VERSION_HEX >= " +
+                       code.get_py_version_hex(self.min_python_version))
         code.putln("%s, /*%s*/" % (value, self.slot_name))
+        if self.min_python_version is not None:
+            code.putln("#endif")
 
     # Some C implementations have trouble statically 
     # initialising a global with a pointer to an extern 
@@ -175,8 +181,10 @@ class MethodSlot(SlotDescriptor):
     #  method_name  string           The __xxx__ name of the method
     #  default      string or None   Default value of the slot
     
-    def __init__(self, signature, slot_name, method_name, default = None):
-        SlotDescriptor.__init__(self, slot_name)
+    def __init__(self, signature, slot_name, method_name,
+                 default = None, min_python_version = None):
+        SlotDescriptor.__init__(self, slot_name,
+                                min_python_version = min_python_version)
         self.signature = signature
         self.slot_name = slot_name
         self.method_name = method_name
@@ -493,7 +501,7 @@ PyNumberMethods = (
     MethodSlot(ibinaryfunc, "nb_inplace_true_divide", "__itruediv__"),
 
     # Added in release 2.5
-    MethodSlot(unaryfunc, "nb_index", "__index__"),
+    MethodSlot(unaryfunc, "nb_index", "__index__", min_python_version=(2,5)),
 )
 
 PySequenceMethods = (