further refinement

diff --cc lib/sqlalchemy/dialects/oracle/cx_oracle.py
index b9f567d34414b24003b994ff3630afbda75f5daf,75e6cadf51c632c9da5bef7f5b4630818261eb57..ab92cc46637f33cb0fed2d37a3d6f583afde4a9c
--- 1/lib/sqlalchemy/dialects/oracle/cx_oracle.py
--- 2/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@@ -329,35 -341,36 +329,37 @@@ class Oracle_cx_oracle(OracleDialect)
          self.auto_setinputsizes = auto_setinputsizes
          self.auto_convert_lobs = auto_convert_lobs
          
--        def vers(num):
--            return tuple([int(x) for x in num.split('.')])
--
          if hasattr(self.dbapi, 'version'):
--            cx_oracle_ver = vers(self.dbapi.version)
++            cx_oracle_ver = tuple([int(x) for x in self.dbapi.version.split('.')])
              self.supports_unicode_binds = cx_oracle_ver >= (5, 0)
              self._cx_oracle_native_nvarchar = cx_oracle_ver >= (5, 0)
-            
-         if self.dbapi is not None and not hasattr(self.dbapi, 'UNICODE'):
-              # cx_Oracle WITH_UNICODE mode.  *only* python
-              # unicode objects accepted for anything
-              self._cx_oracle_string_types = set([self.dbapi.STRING, self.dbapi.NCLOB])
-              self.supports_unicode_statements = True
-              self.supports_unicode_binds = True
-              self._cx_oracle_with_unicode = True
 -        else:
 -            cx_oracle_ver = None
++        else:  
++           cx_oracle_ver = None
+             
++        def types(*names):
++            return set([getattr(self.dbapi, name, None) for name in names]).difference([None])
++
++        self._cx_oracle_string_types = types("STRING", "UNICODE", "NCLOB", "CLOB")
++        self._cx_oracle_unicode_types = types("UNICODE", "NCLOB")
++        self._cx_oracle_binary_types = types("BFILE", "CLOB", "NCLOB", "BLOB") 
++
+         if cx_oracle_ver is None:
+             # this occurs in tests with mock DBAPIs
+             self._cx_oracle_string_types = set()
+             self._cx_oracle_with_unicode = False
+         elif not hasattr(self.dbapi, 'UNICODE'):
+             # cx_Oracle WITH_UNICODE mode.  *only* python
+             # unicode objects accepted for anything
 -            self._cx_oracle_string_types = set([self.dbapi.STRING])
+             self.supports_unicode_statements = True
+             self.supports_unicode_binds = True
+             self._cx_oracle_with_unicode = True
          else:
-              self._cx_oracle_with_unicode = False
-              if self.dbapi is not None:
-                  self._cx_oracle_string_types = set([self.dbapi.UNICODE, self.dbapi.NCLOB, self.dbapi.STRING])
-                  self._cx_oracle_unicode_types = set([self.dbapi.UNICODE, self.dbapi.NCLOB])
-              else:
-                  self._cx_oracle_string_types = set()
- 
-        
-         if self.dbapi is None or \
+             self._cx_oracle_with_unicode = False
 -            self._cx_oracle_string_types = set([self.dbapi.UNICODE, self.dbapi.STRING])
 - 
 -        if self.dbapi is None or \
++
++        if cx_oracle_ver is None or \
                      not self.auto_convert_lobs or \
                      not hasattr(self.dbapi, 'CLOB'):
              self.dbapi_type_map = {}
--            self._cx_oracle_binary_types = set()
          else:
              # only use this for LOB objects.  using it for strings, dates
              # etc. leads to a little too much magic, reflection doesn't know if it should
@@@ -368,9 -381,9 +370,6 @@@
                  self.dbapi.BLOB: oracle.BLOB(),
                  self.dbapi.BINARY: oracle.RAW(),
              }
--            self._cx_oracle_binary_types = set([getattr(self.dbapi, k) for k in 
--                                          ["BFILE", "CLOB", "NCLOB", "BLOB"] 
--                                          if hasattr(self.dbapi, k)])
      
      @classmethod
      def dbapi(cls):