From 25ae68ce6c011d4284eb6df0c559df9d13746ea9 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 3 Feb 2009 03:50:39 +0000
Subject: [PATCH] Register decimals as numbers.Number

---
 Lib/decimal.py           | 7 +++++++
 Lib/test/test_decimal.py | 7 +++++++
 Misc/NEWS                | 3 ++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Lib/decimal.py b/Lib/decimal.py
index e9280c59b28a..7b1308d1f400 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -135,6 +135,7 @@ __all__ = [
 ]
 
 import copy as _copy
+import numbers as _numbers
 
 try:
     from collections import namedtuple as _namedtuple
@@ -3654,6 +3655,12 @@ def _dec_from_triple(sign, coefficient, exponent, special=False):
 
     return self
 
+# Register Decimal as a kind of Number (an abstract base class).
+# However, do not register it as Real (because Decimals are not
+# interoperable with floats).
+_numbers.Number.register(Decimal)
+
+
 ##### Context class #######################################################
 
 
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index fde37fe0b4a3..6b51d13b099f 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -30,6 +30,7 @@ import os, sys
 import pickle, copy
 import unittest
 from decimal import *
+import numbers
 from test.support import (TestSkipped, run_unittest, run_doctest,
                                is_resource_enabled)
 import random
@@ -1389,6 +1390,12 @@ class DecimalUsabilityTest(unittest.TestCase):
 
 class DecimalPythonAPItests(unittest.TestCase):
 
+    def test_abc(self):
+        self.assert_(issubclass(Decimal, numbers.Number))
+        self.assert_(not issubclass(Decimal, numbers.Real))
+        self.assert_(isinstance(Decimal(0), numbers.Number))
+        self.assert_(not isinstance(Decimal(0), numbers.Real))
+
     def test_pickle(self):
         d = Decimal('-3.141590000')
         p = pickle.dumps(d)
diff --git a/Misc/NEWS b/Misc/NEWS
index b516a637821e..ae32ca16636f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -152,7 +152,8 @@ Library
   rather than delaying the close by waiting for garbage collection to do it.
 
 - Issue #4998: Decimal no longer subclasses from or is registered to
-  numbers.Real.
+  numbers.Real.  Instead, it is registered to numbers.Number so that
+  isinstance(d, Number) will work.
 
 - Issue #4867: Fixed a crash in ctypes when passing a string to a
   function without defining argtypes.
-- 
2.47.3