Merged revisions 71832 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r71832 | mark.dickinson | 2009-04-24 14:56:07 +0100 (Fri, 24 Apr 2009) | 3 lines
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 5242f8f..fcebb4f 100755
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -54,7 +54,7 @@
__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 Rational.
Takes a string like '3/2' or '1.5', another Rational, or a
@@ -63,8 +63,13 @@
"""
self = super(Fraction, cls).__new__(cls)
- if not isinstance(numerator, int) and denominator == 1:
- if isinstance(numerator, str):
+ if denominator is None:
+ if isinstance(numerator, numbers.Rational):
+ self._numerator = numerator.numerator
+ self._denominator = numerator.denominator
+ return self
+
+ elif isinstance(numerator, str):
# Handle construction from strings.
m = _RATIONAL_FORMAT.match(numerator)
if m is None:
@@ -91,18 +96,22 @@
if m.group('sign') == '-':
numerator = -numerator
- elif isinstance(numerator, numbers.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, numbers.Rational) and
+ isinstance(denominator, numbers.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