Issue 4998: Decimal should not subclass or register with numbers.Real.
diff --git a/Lib/decimal.py b/Lib/decimal.py
index b486d36..26bc8ef 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -134,7 +134,6 @@
'setcontext', 'getcontext', 'localcontext'
]
-import numbers as _numbers
import copy as _copy
import math as _math
@@ -501,7 +500,11 @@
##### Decimal class #######################################################
-class Decimal(_numbers.Real):
+# Do not subclass Decimal from numbers.Real and do not register it as such
+# (because Decimals are not interoperable with floats). See the notes in
+# numbers.py for more detail.
+
+class Decimal(object):
"""Floating point class for decimal arithmetic."""
__slots__ = ('_exp','_int','_sign', '_is_special')
@@ -1757,14 +1760,10 @@
>>> round(Decimal('Inf'))
Traceback (most recent call last):
...
- ...
- ...
OverflowError: cannot round an infinity
>>> round(Decimal('NaN'))
Traceback (most recent call last):
...
- ...
- ...
ValueError: cannot round a NaN
If a second argument n is supplied, self is rounded to n