[Zodb-checkins] CVS: Zope/lib/Components/ExtensionClass/src - Missing.c:1.13.10.3

[Jeremy Hylton]

Update of /cvs-repository/Zope/lib/Components/ExtensionClass/src
In directory cvs.zope.org:/tmp/cvs-serv16571

Modified Files:
      Tag: Zope-2_6-branch
	Missing.c 
Log Message:
Backport real fix for coercion bug.


=== Zope/lib/Components/ExtensionClass/src/Missing.c 1.13.10.2 => 1.13.10.3 ===
--- Zope/lib/Components/ExtensionClass/src/Missing.c:1.13.10.2	Fri May  9 16:03:02 2003
+++ Zope/lib/Components/ExtensionClass/src/Missing.c	Fri May  9 16:59:35 2003
@@ -78,14 +78,19 @@
   return 0;
 }
 
-/* XXX Why does this type offer to corece at all? */
+/* coerce should return two values of the same type.
+
+   We violate that contract in a controlled way, by always coercing
+   the other object to Py_None.  We are guaranteed that our tp_compare
+   will be called because Py_None does not define a tp_compare.
+*/
+
 static int
 Missing_coerce(PyObject **pv, PyObject **pw)
 {
-    if (!(*pw)->ob_type->tp_as_number)
-	return 1;
     Py_INCREF(*pv);
-    Py_INCREF(*pw);
+    Py_INCREF(Py_None);
+    *pw = Py_None;
     return 0;
 }
 
@@ -221,10 +226,16 @@
   return self;
 }
 
+/* All Missing objects are equal to each other, but we have
+   specially arranged for Py_None to be passed as m2 via
+   Missing_coerce().  So be prepared for Py_None where
+   a Missing is expected.
+*/
+
 static int
 Missing_cmp(Missing *m1, Missing *m2)
 {
-  return m1->ob_type != m2->ob_type ;
+    return Py_None == (PyObject *)m2;
 }
 
 static PyExtensionClass MissingType = {
@@ -253,7 +264,7 @@
   0L,0L,
   "Represent totally unknown quantities\n"
   "\n"
-  "Missing values are used to represent numberic quantities that are\n"
+  "Missing values are used to represent numeric quantities that are\n"
   "unknown.  They support all mathematical operations except\n"
   "conversions by returning themselves.\n",
   METHOD_CHAIN(NULL)
@@ -295,65 +306,5 @@
   PyDict_SetItemString(d, "Value", theValue);
   PyDict_SetItemString(d, "V", theValue); 
   PyDict_SetItemString(d, "MV", theValue); 
-	
-  /* Check for errors */
-  if (PyErr_Occurred())
-    Py_FatalError("can't initialize module Missing");
 }
-
-/*****************************************************************************
-Revision Log:
-
-  $Log$
-  Revision 1.13.10.2  2003/05/09 20:03:02  jeremy
-  Backport coercion bug fix.
-
-  Revision 1.13.10.1  2002/11/13 16:40:01  jeremy
-  Backport: Fix includes before Python.h.
-
-  Revision 1.13  2002/06/10 22:48:46  jeremy
-  Update ExtensionClass to ZPL 2.0.
-
-  Revision 1.12  2002/01/25 15:34:06  gvanrossum
-  Get rid of __version__, as Jim recommends.  Use $ from docstring instead.
-
-  Revision 1.11  2001/03/28 14:06:51  jeremy
-  gcc -Wall cleanup
-      - make function decls prototypes
-      - remove unreferenced functions
-
-  Revision 1.10  1999/08/25 20:15:29  jim
-  Made getattr a bit pickler to prevent getting attributes like "%f5.3".
-
-  Revision 1.9  1999/06/10 20:09:47  jim
-  Updated to use new ExtensionClass destructor protocol.
-
-  Revision 1.8  1998/11/17 19:54:33  jim
-  new copyright.
-
-  Revision 1.7  1997/10/03 14:43:27  jim
-  Fixed comparison bug, again :-(
-
-  Revision 1.6  1997/09/23 16:06:03  jim
-  Added MV member.
-
-  Revision 1.5  1997/09/23 15:17:12  jim
-  Added cmp.
-
-  Revision 1.4  1997/09/18 21:01:33  jim
-  Added check to getattr to fail on methods that begin with underscore.
-  Note that Missing really defeats testing from protocols by testing for
-  attributes.
-
-  Revision 1.3  1997/09/17 22:49:35  jim
-  Fixed refcount bug.
-  Added logic so:  Missing.Value.spam() returns Missing.Value.
-  Added logic to make Missing.Value picklable.
-
-  Revision 1.2  1997/07/02 20:19:37  jim
-  Got rid of unused macros and ErrorObject.
-
-  Revision 1.1  1997/07/01 21:36:34  jim
-
-
-*****************************************************************************/
+