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Issue #8188: Comparisons between Decimal objects and other numeric

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objects (Fraction, float, complex, int) now all function as expected.
This commit is contained in:
Mark Dickinson 2010-06-11 10:44:52 +00:00
parent bfd73faf86
commit 08ade6faa0
5 changed files with 112 additions and 25 deletions
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43
Lib/decimal.py
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@ -862,7 +862,7 @@ class Decimal(object):
# that specified by IEEE 754.
def __eq__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other, equality_op=True)
if other is NotImplemented:
return other
if self._check_nans(other, context):
@ -870,7 +870,7 @@ class Decimal(object):
return self._cmp(other) == 0
def __ne__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other, equality_op=True)
if other is NotImplemented:
return other
if self._check_nans(other, context):
@ -879,7 +879,7 @@ class Decimal(object):
def __lt__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other)
if other is NotImplemented:
return other
ans = self._compare_check_nans(other, context)
@ -888,7 +888,7 @@ class Decimal(object):
return self._cmp(other) < 0
def __le__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other)
if other is NotImplemented:
return other
ans = self._compare_check_nans(other, context)
@ -897,7 +897,7 @@ class Decimal(object):
return self._cmp(other) <= 0
def __gt__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other)
if other is NotImplemented:
return other
ans = self._compare_check_nans(other, context)
@ -906,7 +906,7 @@ class Decimal(object):
return self._cmp(other) > 0
def __ge__(self, other, context=None):
other = _convert_other(other, allow_float = True)
self, other = _convert_for_comparison(self, other)
if other is NotImplemented:
return other
ans = self._compare_check_nans(other, context)
@ -5860,6 +5860,37 @@ def _convert_other(other, raiseit=False, allow_float=False):
raise TypeError("Unable to convert %s to Decimal" % other)
return NotImplemented
def _convert_for_comparison(self, other, equality_op=False):
"""Given a Decimal instance self and a Python object other, return
an pair (s, o) of Decimal instances such that "s op o" is
equivalent to "self op other" for any of the 6 comparison
operators "op".
"""
if isinstance(other, Decimal):
return self, other
# Comparison with a Rational instance (also includes integers):
# self op n/d <=> self*d op n (for n and d integers, d positive).
# A NaN or infinity can be left unchanged without affecting the
# comparison result.
if isinstance(other, _numbers.Rational):
if not self._is_special:
self = _dec_from_triple(self._sign,
str(int(self._int) * other.denominator),
self._exp)
return self, Decimal(other.numerator)
# Comparisons with float and complex types. == and != comparisons
# with complex numbers should succeed, returning either True or False
# as appropriate. Other comparisons return NotImplemented.
if equality_op and isinstance(other, _numbers.Complex) and other.imag == 0:
other = other.real
if isinstance(other, float):
return self, Decimal.from_float(other)
return NotImplemented, NotImplemented
##### Setup Specific Contexts ############################################
# The default context prototype used by Context()