[Python-checkins] cpython: Issue #25971: Optimized creating Fractions from floats by 2 times and from
serhiy.storchaka
python-checkins at python.org
Tue Dec 29 15:34:44 EST 2015
https://hg.python.org/cpython/rev/284026a8af9e
changeset: 99716:284026a8af9e
user: Serhiy Storchaka <storchaka at gmail.com>
date: Tue Dec 29 22:34:23 2015 +0200
summary:
Issue #25971: Optimized creating Fractions from floats by 2 times and from
Decimals by 3 times.
Unified error messages in float.as_integer_ratio(), Decimal.as_integer_ratio(),
and Fraction constructors.
files:
Lib/_pydecimal.py | 6 +---
Lib/fractions.py | 32 +++----------------------
Lib/test/test_fractions.py | 14 +++++-----
Misc/NEWS | 3 ++
Objects/floatobject.c | 12 ++++----
5 files changed, 22 insertions(+), 45 deletions(-)
diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py
--- a/Lib/_pydecimal.py
+++ b/Lib/_pydecimal.py
@@ -1026,11 +1026,9 @@
"""
if self._is_special:
if self.is_nan():
- raise ValueError("Cannot pass NaN "
- "to decimal.as_integer_ratio.")
+ raise ValueError("cannot convert NaN to integer ratio")
else:
- raise OverflowError("Cannot pass infinity "
- "to decimal.as_integer_ratio.")
+ raise OverflowError("cannot convert Infinity to integer ratio")
if not self:
return 0, 1
diff --git a/Lib/fractions.py b/Lib/fractions.py
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -125,17 +125,9 @@
self._denominator = numerator.denominator
return self
- elif isinstance(numerator, float):
- # Exact conversion from float
- value = Fraction.from_float(numerator)
- self._numerator = value._numerator
- self._denominator = value._denominator
- return self
-
- elif isinstance(numerator, Decimal):
- value = Fraction.from_decimal(numerator)
- self._numerator = value._numerator
- self._denominator = value._denominator
+ elif isinstance(numerator, (float, Decimal)):
+ # Exact conversion
+ self._numerator, self._denominator = numerator.as_integer_ratio()
return self
elif isinstance(numerator, str):
@@ -210,10 +202,6 @@
elif not isinstance(f, float):
raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
(cls.__name__, f, type(f).__name__))
- if math.isnan(f):
- raise ValueError("Cannot convert %r to %s." % (f, cls.__name__))
- if math.isinf(f):
- raise OverflowError("Cannot convert %r to %s." % (f, cls.__name__))
return cls(*f.as_integer_ratio())
@classmethod
@@ -226,19 +214,7 @@
raise TypeError(
"%s.from_decimal() only takes Decimals, not %r (%s)" %
(cls.__name__, dec, type(dec).__name__))
- if dec.is_infinite():
- raise OverflowError(
- "Cannot convert %s to %s." % (dec, cls.__name__))
- if dec.is_nan():
- raise ValueError("Cannot convert %s to %s." % (dec, cls.__name__))
- sign, digits, exp = dec.as_tuple()
- digits = int(''.join(map(str, digits)))
- if sign:
- digits = -digits
- if exp >= 0:
- return cls(digits * 10 ** exp)
- else:
- return cls(digits, 10 ** -exp)
+ return cls(*dec.as_integer_ratio())
def limit_denominator(self, max_denominator=1000000):
"""Closest Fraction to self with denominator at most max_denominator.
diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
--- a/Lib/test/test_fractions.py
+++ b/Lib/test/test_fractions.py
@@ -263,13 +263,13 @@
nan = inf - inf
# bug 16469: error types should be consistent with float -> int
self.assertRaisesMessage(
- OverflowError, "Cannot convert inf to Fraction.",
+ OverflowError, "cannot convert Infinity to integer ratio",
F.from_float, inf)
self.assertRaisesMessage(
- OverflowError, "Cannot convert -inf to Fraction.",
+ OverflowError, "cannot convert Infinity to integer ratio",
F.from_float, -inf)
self.assertRaisesMessage(
- ValueError, "Cannot convert nan to Fraction.",
+ ValueError, "cannot convert NaN to integer ratio",
F.from_float, nan)
def testFromDecimal(self):
@@ -284,16 +284,16 @@
# bug 16469: error types should be consistent with decimal -> int
self.assertRaisesMessage(
- OverflowError, "Cannot convert Infinity to Fraction.",
+ OverflowError, "cannot convert Infinity to integer ratio",
F.from_decimal, Decimal("inf"))
self.assertRaisesMessage(
- OverflowError, "Cannot convert -Infinity to Fraction.",
+ OverflowError, "cannot convert Infinity to integer ratio",
F.from_decimal, Decimal("-inf"))
self.assertRaisesMessage(
- ValueError, "Cannot convert NaN to Fraction.",
+ ValueError, "cannot convert NaN to integer ratio",
F.from_decimal, Decimal("nan"))
self.assertRaisesMessage(
- ValueError, "Cannot convert sNaN to Fraction.",
+ ValueError, "cannot convert NaN to integer ratio",
F.from_decimal, Decimal("snan"))
def testLimitDenominator(self):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -126,6 +126,9 @@
Library
-------
+- Issue #25971: Optimized creating Fractions from floats by 2 times and from
+ Decimals by 3 times.
+
- Issue #25802: Document as deprecated the remaining implementations of
importlib.abc.Loader.load_module().
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -1466,14 +1466,14 @@
CONVERT_TO_DOUBLE(v, self);
if (Py_IS_INFINITY(self)) {
- PyErr_SetString(PyExc_OverflowError,
- "Cannot pass infinity to float.as_integer_ratio.");
- return NULL;
+ PyErr_SetString(PyExc_OverflowError,
+ "cannot convert Infinity to integer ratio");
+ return NULL;
}
if (Py_IS_NAN(self)) {
- PyErr_SetString(PyExc_ValueError,
- "Cannot pass NaN to float.as_integer_ratio.");
- return NULL;
+ PyErr_SetString(PyExc_ValueError,
+ "cannot convert NaN to integer ratio");
+ return NULL;
}
PyFPE_START_PROTECT("as_integer_ratio", goto error);
--
Repository URL: https://hg.python.org/cpython
More information about the Python-checkins
mailing list