diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 43eaba935a164a..bbc577617a9473 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -29,6 +29,17 @@ noted otherwise, all return values are floats.
Number-theoretic and representation functions
---------------------------------------------
+.. function:: as_integer_ratio(number)
+
+ Return integer ratio.
+
+ This function returns ``number.as_integer_ratio()`` if the argument has
+ the ``as_integer_ratio()`` method, otherwise it returns a pair
+ ``(number.numerator, number.denominator)``.
+
+ .. versionadded:: 3.9
+
+
.. function:: ceil(x)
Return the ceiling of *x*, the smallest integer greater than or equal to *x*.
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 61d9e745e87ccf..acdd418c08b2b7 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -109,6 +109,14 @@ New Modules
Improved Modules
================
+
+math
+----
+
+Added new function :func:`math.as_integer_ratio`.
+(Contributed by Serhiy Storchaka in :issue:``.)
+
+
threading
---------
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 7443bd3e0c6af9..05eda36b438dac 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -115,22 +115,7 @@ def __new__(cls, numerator=0, denominator=None, *, _normalize=True):
self = super(Fraction, cls).__new__(cls)
if denominator is None:
- 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
-
- elif isinstance(numerator, (float, Decimal)):
- # Exact conversion
- self._numerator, self._denominator = numerator.as_integer_ratio()
- return self
-
- elif isinstance(numerator, str):
+ if isinstance(numerator, str):
# Handle construction from strings.
m = _RATIONAL_FORMAT.match(numerator)
if m is None:
@@ -156,10 +141,13 @@ def __new__(cls, numerator=0, denominator=None, *, _normalize=True):
denominator *= 10**-exp
if m.group('sign') == '-':
numerator = -numerator
-
else:
- raise TypeError("argument should be a string "
- "or a Rational instance")
+ try:
+ self._numerator, self._denominator = math.as_integer_ratio(numerator)
+ return self
+ except TypeError:
+ raise TypeError("argument should be a string or a number, "
+ "not %s" % type(numerator).__name__) from None
elif type(numerator) is int is type(denominator):
pass # *very* normal case
diff --git a/Lib/statistics.py b/Lib/statistics.py
index 77291dd62cb90e..b11047cb703421 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -225,27 +225,11 @@ def _exact_ratio(x):
x is expected to be an int, Fraction, Decimal or float.
"""
try:
- # Optimise the common case of floats. We expect that the most often
- # used numeric type will be builtin floats, so try to make this as
- # fast as possible.
- if type(x) is float or type(x) is Decimal:
- return x.as_integer_ratio()
- try:
- # x may be an int, Fraction, or Integral ABC.
- return (x.numerator, x.denominator)
- except AttributeError:
- try:
- # x may be a float or Decimal subclass.
- return x.as_integer_ratio()
- except AttributeError:
- # Just give up?
- pass
+ return math.as_integer_ratio(x)
except (OverflowError, ValueError):
# float NAN or INF.
assert not _isfinite(x)
return (x, None)
- msg = "can't convert type '{}' to numerator/denominator"
- raise TypeError(msg.format(type(x).__name__))
def _convert(value, T):
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index c237bc1942e655..492e024250bb11 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -12,6 +12,8 @@
import random
import struct
import sys
+from decimal import Decimal
+from fractions import Fraction
eps = 1E-05
@@ -293,6 +295,33 @@ def testAcosh(self):
self.assertRaises(ValueError, math.acosh, NINF)
self.assertTrue(math.isnan(math.acosh(NAN)))
+ def testAsIntegerRatio(self):
+ as_integer_ratio = math.as_integer_ratio
+ self.assertEqual(as_integer_ratio(0), (0, 1))
+ self.assertEqual(as_integer_ratio(3), (3, 1))
+ self.assertEqual(as_integer_ratio(-3), (-3, 1))
+ self.assertEqual(as_integer_ratio(False), (0, 1))
+ self.assertEqual(as_integer_ratio(True), (1, 1))
+ self.assertEqual(as_integer_ratio(0.0), (0, 1))
+ self.assertEqual(as_integer_ratio(-0.0), (0, 1))
+ self.assertEqual(as_integer_ratio(0.875), (7, 8))
+ self.assertEqual(as_integer_ratio(-0.875), (-7, 8))
+ self.assertEqual(as_integer_ratio(Decimal('0')), (0, 1))
+ self.assertEqual(as_integer_ratio(Decimal('0.875')), (7, 8))
+ self.assertEqual(as_integer_ratio(Decimal('-0.875')), (-7, 8))
+ self.assertEqual(as_integer_ratio(Fraction(0)), (0, 1))
+ self.assertEqual(as_integer_ratio(Fraction(7, 8)), (7, 8))
+ self.assertEqual(as_integer_ratio(Fraction(-7, 8)), (-7, 8))
+
+ self.assertRaises(OverflowError, as_integer_ratio, float('inf'))
+ self.assertRaises(OverflowError, as_integer_ratio, float('-inf'))
+ self.assertRaises(ValueError, as_integer_ratio, float('nan'))
+ self.assertRaises(OverflowError, as_integer_ratio, Decimal('inf'))
+ self.assertRaises(OverflowError, as_integer_ratio, Decimal('-inf'))
+ self.assertRaises(ValueError, as_integer_ratio, Decimal('nan'))
+
+ self.assertRaises(TypeError, as_integer_ratio, '0')
+
def testAsin(self):
self.assertRaises(TypeError, math.asin)
self.ftest('asin(-1)', math.asin(-1), -math.pi/2)
diff --git a/Misc/NEWS.d/next/Library/2019-08-11-16-55-46.bpo-37822.7xHl1w.rst b/Misc/NEWS.d/next/Library/2019-08-11-16-55-46.bpo-37822.7xHl1w.rst
new file mode 100644
index 00000000000000..37e9c819b3bb21
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-08-11-16-55-46.bpo-37822.7xHl1w.rst
@@ -0,0 +1 @@
+Added :func:`math.as_integer_ratio`.
diff --git a/Modules/clinic/mathmodule.c.h b/Modules/clinic/mathmodule.c.h
index 84561b955787b7..701e1c932b83f2 100644
--- a/Modules/clinic/mathmodule.c.h
+++ b/Modules/clinic/mathmodule.c.h
@@ -712,4 +712,13 @@ math_comb(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
exit:
return return_value;
}
-/*[clinic end generated code: output=f93cfe13ab2fdb4e input=a9049054013a1b77]*/
+
+PyDoc_STRVAR(math_as_integer_ratio__doc__,
+"as_integer_ratio($module, x, /)\n"
+"--\n"
+"\n"
+"greatest common divisor of x and y");
+
+#define MATH_AS_INTEGER_RATIO_METHODDEF \
+ {"as_integer_ratio", (PyCFunction)math_as_integer_ratio, METH_O, math_as_integer_ratio__doc__},
+/*[clinic end generated code: output=f9722232fc321d17 input=a9049054013a1b77]*/
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index e1b46ec384a373..76bc1cc1c9ed4f 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -3306,9 +3306,83 @@ math_comb_impl(PyObject *module, PyObject *n, PyObject *k)
}
+/*[clinic input]
+math.as_integer_ratio
+ x: object
+ /
+greatest common divisor of x and y
+[clinic start generated code]*/
+
+static PyObject *
+math_as_integer_ratio(PyObject *module, PyObject *x)
+/*[clinic end generated code: output=1844868fd4efb2f1 input=d7f2e8ffd51c6599]*/
+{
+ _Py_IDENTIFIER(as_integer_ratio);
+ _Py_IDENTIFIER(numerator);
+ _Py_IDENTIFIER(denominator);
+ PyObject *ratio, *as_integer_ratio, *numerator, *denominator;
+
+ if (PyLong_CheckExact(x)) {
+ return PyTuple_Pack(2, x, _PyLong_One);
+ }
+
+ if (_PyObject_LookupAttrId(x, &PyId_as_integer_ratio, &as_integer_ratio) < 0) {
+ return NULL;
+ }
+ if (as_integer_ratio) {
+ ratio = _PyObject_CallNoArg(as_integer_ratio);
+ Py_DECREF(as_integer_ratio);
+ if (ratio == NULL) {
+ return NULL;
+ }
+ if (!PyTuple_Check(ratio)) {
+ PyErr_Format(PyExc_TypeError,
+ "unexpected return type from as_integer_ratio(): "
+ "expected tuple, got '%.200s'",
+ Py_TYPE(ratio)->tp_name);
+ Py_DECREF(ratio);
+ return NULL;
+ }
+ if (PyTuple_GET_SIZE(ratio) != 2) {
+ PyErr_SetString(PyExc_ValueError,
+ "as_integer_ratio() must return a 2-tuple");
+ Py_DECREF(ratio);
+ return NULL;
+ }
+ }
+ else {
+ if (_PyObject_LookupAttrId(x, &PyId_numerator, &numerator) < 0) {
+ return NULL;
+ }
+ if (numerator == NULL) {
+ PyErr_Format(PyExc_TypeError,
+ "required a number, not '%.200s'",
+ Py_TYPE(x)->tp_name);
+ return NULL;
+ }
+ if (_PyObject_LookupAttrId(x, &PyId_denominator, &denominator) < 0) {
+ Py_DECREF(numerator);
+ return NULL;
+ }
+ if (denominator == NULL) {
+ Py_DECREF(numerator);
+ PyErr_Format(PyExc_TypeError,
+ "required a number, not '%.200s'",
+ Py_TYPE(x)->tp_name);
+ return NULL;
+ }
+ ratio = PyTuple_Pack(2, numerator, denominator);
+ Py_DECREF(numerator);
+ Py_DECREF(denominator);
+ }
+ return ratio;
+}
+
+
static PyMethodDef math_methods[] = {
{"acos", math_acos, METH_O, math_acos_doc},
{"acosh", math_acosh, METH_O, math_acosh_doc},
+ MATH_AS_INTEGER_RATIO_METHODDEF
{"asin", math_asin, METH_O, math_asin_doc},
{"asinh", math_asinh, METH_O, math_asinh_doc},
{"atan", math_atan, METH_O, math_atan_doc},
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