More ducktyping. Add more tests.

python · serhiy-storchaka · Jul 19, 2024 · Jun 8, 2024 · Jun 9, 2024 · Jul 9, 2024
commit 07bcf8121f8b394f97e4f1ee81f527cd10fffad5
diff --git a/Doc/library/fractions.rst b/Doc/library/fractions.rst
@@ -26,12 +26,11 @@ another rational number, or from a string.
    with value ``numerator/denominator``. If *denominator* is ``0``, it
    raises a :exc:`ZeroDivisionError`.
 
-   The second version requires that
-   *number* is an instance of :class:`numbers.Rational` or is an instance
-   of :class:`numbers.Number` and has the :meth:`!as_integer_ratio` method
+   The second version requires that *number* is an instance of
+   :class:`numbers.Rational` or has the :meth:`!as_integer_ratio` method
    (this includes :class:`float` and :class:`decimal.Decimal`).
    It returns a :class:`Fraction` instance with exactly the same value.
-   Assumed, that the :meth:`~as_integer_ratio` method returns a pair
+   Assumed, that the :meth:`!as_integer_ratio` method returns a pair
    of coprime integers and last one is positive.
    Note that due to the
    usual issues with binary floating-point (see :ref:`tut-fp-issues`), the
@@ -115,7 +114,7 @@ another rational number, or from a string.
       now supports fill, alignment, sign handling, minimum width and grouping.
 
    .. versionchanged:: 3.14
-      The :class:`Fraction` constructor now accepts any numbers with the
+      The :class:`Fraction` constructor now accepts any objects with the
       :meth:`!as_integer_ratio` method.
 
    .. attribute:: numerator

diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
@@ -103,7 +103,7 @@ ast
 fractions
 ---------
 
-Added support for converting any numbers that have the
+Added support for converting any objects that have the
 :meth:`!as_integer_ratio` method to a :class:`~fractions.Fraction`.
 (Contributed by Serhiy Storchaka in :gh:`82017`.)
 

diff --git a/Lib/fractions.py b/Lib/fractions.py
@@ -244,7 +244,7 @@ def __new__(cls, numerator=0, denominator=None):
                 return self
 
             elif (isinstance(numerator, float) or
-                  (isinstance(numerator, numbers.Number) and
+                  (not isinstance(numerator, type) and
                    hasattr(numerator, 'as_integer_ratio'))):
                 # Exact conversion
                 self._numerator, self._denominator = numerator.as_integer_ratio()

diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
@@ -360,22 +360,34 @@ def __init__(self, ratio):
                 self._ratio = ratio
             def as_integer_ratio(self):
                 return self._ratio
-        class RatioNumber(Ratio):
-            pass
-        numbers.Number.register(RatioNumber)
 
-        self.assertEqual((7, 3), _components(F(RatioNumber((7, 3)))))
-        # not a number
-        self.assertRaises(TypeError, F, Ratio((7, 3)))
+        self.assertEqual((7, 3), _components(F(Ratio((7, 3)))))
+        errmsg = "argument should be a string or a number"
         # the type also has an "as_integer_ratio" attribute.
-        self.assertRaises(TypeError, F, RatioNumber)
+        self.assertRaisesRegex(TypeError, errmsg, F, Ratio)
         # bad ratio
-        self.assertRaises(TypeError, F, RatioNumber(7))
-        self.assertRaises(ValueError, F, RatioNumber((7,)))
-        self.assertRaises(ValueError, F, RatioNumber((7, 3, 1)))
+        self.assertRaises(TypeError, F, Ratio(7))
+        self.assertRaises(ValueError, F, Ratio((7,)))
+        self.assertRaises(ValueError, F, Ratio((7, 3, 1)))
         # only single-argument form
-        self.assertRaises(TypeError, F, RatioNumber((3, 7)), 11)
-        self.assertRaises(TypeError, F, 2, RatioNumber((-10, 9)))
+        self.assertRaises(TypeError, F, Ratio((3, 7)), 11)
+        self.assertRaises(TypeError, F, 2, Ratio((-10, 9)))
+
+        # as_integer_ratio not defined in a class
+        class A:
+            pass
+        a = A()
+        a.as_integer_ratio = lambda: (9, 5)
+        self.assertEqual((9, 5), _components(F(a)))
+
+        # as_integer_ratio defined in a metaclass
+        class M(type):
+            def as_integer_ratio(self):
+                return (11, 9)
+        class B(metaclass=M):
+            pass
+        self.assertRaisesRegex(TypeError, errmsg, F, B)
+        self.assertRaisesRegex(TypeError, errmsg, F, B())
 
     def testFromString(self):
         self.assertEqual((5, 1), _components(F("5")))

diff --git a/Misc/NEWS.d/next/Library/2024-06-08-17-41-11.gh-issue-82017.WpSTGi.rst b/Misc/NEWS.d/next/Library/2024-06-08-17-41-11.gh-issue-82017.WpSTGi.rst
@@ -1,2 +1,2 @@
-Added support for converting any numbers that have the
+Added support for converting any objects that have the
 :meth:`!as_integer_ratio` method to a :class:`~fractions.Fraction`.