Issue #5812: The two-argument form of the Fraction constructor
now accepts arbitrary Rational instances.
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 7db6b5b..15711ed 100755
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -56,7 +56,7 @@
__slots__ = ('_numerator', '_denominator')
# We're immutable, so use __new__ not __init__
- def __new__(cls, numerator=0, denominator=1):
+ def __new__(cls, numerator=0, denominator=None):
"""Constructs a Fraction.
Takes a string like '3/2' or '1.5', another Fraction, or a
@@ -65,8 +65,13 @@
"""
self = super(Fraction, cls).__new__(cls)
- if type(numerator) not in (int, long) and denominator == 1:
- if isinstance(numerator, basestring):
+ if denominator is None:
+ if isinstance(numerator, Rational):
+ self._numerator = numerator.numerator
+ self._denominator = numerator.denominator
+ return self
+
+ elif isinstance(numerator, basestring):
# Handle construction from strings.
m = _RATIONAL_FORMAT.match(numerator)
if m is None:
@@ -93,18 +98,22 @@
if m.group('sign') == '-':
numerator = -numerator
- elif isinstance(numerator, Rational):
- # Handle copies from other rationals. Integrals get
- # caught here too, but it doesn't matter because
- # denominator is already 1.
- other_rational = numerator
- numerator = other_rational.numerator
- denominator = other_rational.denominator
+ else:
+ raise TypeError("argument should be a string "
+ "or a Rational instance")
+
+ elif (isinstance(numerator, Rational) and
+ isinstance(denominator, Rational)):
+ numerator, denominator = (
+ numerator.numerator * denominator.denominator,
+ denominator.numerator * numerator.denominator
+ )
+ else:
+ raise TypeError("both arguments should be "
+ "Rational instances")
if denominator == 0:
raise ZeroDivisionError('Fraction(%s, 0)' % numerator)
- numerator = operator.index(numerator)
- denominator = operator.index(denominator)
g = gcd(numerator, denominator)
self._numerator = numerator // g
self._denominator = denominator // g