PEP 249: Replace StandardError with Exception

pep-0249.txt

@@ -118,7 +118,7 @@ exceptions or subclasses thereof:
 `Warning`_
     Exception raised for important warnings like data truncations
     while inserting, etc. It must be a subclass of the Python
-    ``StandardError`` (defined in the module exceptions).
+    ``Exception`` [10]_ [11]_.
 
 
 .. _Error:
@@ -128,7 +128,7 @@ exceptions or subclasses thereof:
     exceptions. You can use this to catch all errors with one single
     ``except`` statement. Warnings are not considered errors and thus
     should not use this class as base. It must be a subclass of the
-    Python ``StandardError`` (defined in the module exceptions).
+    Python ``Exception`` [10]_.
 
 
 .. _InterfaceError:
@@ -201,8 +201,8 @@ exceptions or subclasses thereof:
 
 This is the exception inheritance layout::
 
-    StandardError
-    |__Warning
+    Exception [10]_
+    |__Warning [11]_
     |__Error
        |__InterfaceError
        |__DatabaseError
@@ -731,14 +731,12 @@ Implementation Hints for Module Authors
   constructor.
 
 * Here is a snippet of Python code that implements the exception
-  hierarchy defined above::
+  hierarchy defined above [10]_::
 
-        import exceptions
-
-        class Error(exceptions.StandardError):
+        class Error(Exception):
             pass
 
-        class Warning(exceptions.StandardError):
+        class Warning(Exception):
             pass
 
         class InterfaceError(Error):
@@ -1297,6 +1295,23 @@ Footnotes
     ``WHERE`` clause, or clearly document a different interpretation
     of the ``.rowcount`` attribute.
 
+.. [10] In Python 2 and earlier versions of this PEP,
+    ``exceptions.StandardError`` was used as the base class for all
+    DB-API exceptions. Since ``StandardError`` was removed in Python 3,
+    database modules targeting Python 3 should use
+    ``exception.Exception`` as base class instead. Both
+    ``StandardError`` and ``Exception`` are available as builtin
+    objects, so it is not necessary to import the ``exceptions`` module
+    for this. The PEP was updated to use ``Exception`` throughout the
+    text, to avoid confusion. The change should not affect existing
+    modules or uses of those modules, since all DB-API error exception
+    classes are still rooted at the ``Error`` or ``Warning`` classes.
+
+.. [11] In a future revision of the DB-API, the base class for
+    ``Warning`` will likely change to the builtin ``Warning`` class. At
+    the time of writing of the DB-API 2.0 in 1999, the warning framework
+    in Python had not yet existed.
+
 
 Acknowledgements
 ================