From 40f9735486a847130eb52185659a278cf369bb9e Mon Sep 17 00:00:00 2001
From: Georg Brandl <georg@python.org>
Date: Wed, 24 Sep 2014 08:37:55 +0200
Subject: #22464: Speed up common Fraction operations by special-casing several
operations for int-type arguments: constructor and equality test.
Also avoid redundant property lookups in addition and subtraction.
---
Lib/fractions.py | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 57bf7f5..5ddc84c 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -104,7 +104,12 @@ class Fraction(numbers.Rational):
self = super(Fraction, cls).__new__(cls)
if denominator is None:
- if isinstance(numerator, numbers.Rational):
+ if type(numerator) is int:
+ self._numerator = numerator
+ self._denominator = 1
+ return self
+
+ elif isinstance(numerator, numbers.Rational):
self._numerator = numerator.numerator
self._denominator = numerator.denominator
return self
@@ -153,6 +158,9 @@ class Fraction(numbers.Rational):
raise TypeError("argument should be a string "
"or a Rational instance")
+ elif type(numerator) is int is type(denominator):
+ pass # *very* normal case
+
elif (isinstance(numerator, numbers.Rational) and
isinstance(denominator, numbers.Rational)):
numerator, denominator = (
@@ -399,17 +407,17 @@ class Fraction(numbers.Rational):
def _add(a, b):
"""a + b"""
- return Fraction(a.numerator * b.denominator +
- b.numerator * a.denominator,
- a.denominator * b.denominator)
+ da, db = a.denominator, b.denominator
+ return Fraction(a.numerator * db + b.numerator * da,
+ da * db)
__add__, __radd__ = _operator_fallbacks(_add, operator.add)
def _sub(a, b):
"""a - b"""
- return Fraction(a.numerator * b.denominator -
- b.numerator * a.denominator,
- a.denominator * b.denominator)
+ da, db = a.denominator, b.denominator
+ return Fraction(a.numerator * db - b.numerator * da,
+ da * db)
__sub__, __rsub__ = _operator_fallbacks(_sub, operator.sub)
@@ -561,6 +569,8 @@ class Fraction(numbers.Rational):
def __eq__(a, b):
"""a == b"""
+ if type(b) is int:
+ return a._numerator == b and a._denominator == 1
if isinstance(b, numbers.Rational):
return (a._numerator == b.numerator and
a._denominator == b.denominator)
--
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