[Python-checkins] gh-100488: Add is_integer method to fractions.Fraction (#100489)

[hauntsaninja]

https://github.com/python/cpython/commit/e83f88a455261ed53530a960f1514ab7af7d2e82
commit: e83f88a455261ed53530a960f1514ab7af7d2e82
branch: main
author: Shantanu <12621235+hauntsaninja at users.noreply.github.com>
committer: hauntsaninja <12621235+hauntsaninja at users.noreply.github.com>
date: 2023-01-01T01:44:48-07:00
summary:

gh-100488: Add is_integer method to fractions.Fraction (#100489)

files:
A Misc/NEWS.d/next/Library/2022-12-24-04-13-54.gh-issue-100488.Ut8HbE.rst
M Doc/library/fractions.rst
M Lib/fractions.py
M Lib/test/test_fractions.py

diff --git a/Doc/library/fractions.rst b/Doc/library/fractions.rst
index c46d88b2297a..dc9d5fc18215 100644
--- a/Doc/library/fractions.rst
+++ b/Doc/library/fractions.rst
@@ -117,6 +117,12 @@ another rational number, or from a string.
 
       .. versionadded:: 3.8
 
+   .. method:: is_integer()
+
+      Return ``True`` if the Fraction is an integer.
+
+      .. versionadded:: 3.12
+
    .. classmethod:: from_float(flt)
 
       Alternative constructor which only accepts instances of
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 75c7df14e1b9..4302f3f1b98d 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -225,6 +225,10 @@ def from_decimal(cls, dec):
                 (cls.__name__, dec, type(dec).__name__))
         return cls(*dec.as_integer_ratio())
 
+    def is_integer(self):
+        """Return True if the Fraction is an integer."""
+        return self._denominator == 1
+
     def as_integer_ratio(self):
         """Return the integer ratio as a tuple.
 
diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
index 7fa9dbea905b..819d680fd88e 100644
--- a/Lib/test/test_fractions.py
+++ b/Lib/test/test_fractions.py
@@ -340,6 +340,19 @@ def testFromDecimal(self):
             ValueError, "cannot convert NaN to integer ratio",
             F.from_decimal, Decimal("snan"))
 
+    def test_is_integer(self):
+        self.assertTrue(F(1, 1).is_integer())
+        self.assertTrue(F(-1, 1).is_integer())
+        self.assertTrue(F(1, -1).is_integer())
+        self.assertTrue(F(2, 2).is_integer())
+        self.assertTrue(F(-2, 2).is_integer())
+        self.assertTrue(F(2, -2).is_integer())
+
+        self.assertFalse(F(1, 2).is_integer())
+        self.assertFalse(F(-1, 2).is_integer())
+        self.assertFalse(F(1, -2).is_integer())
+        self.assertFalse(F(-1, -2).is_integer())
+
     def test_as_integer_ratio(self):
         self.assertEqual(F(4, 6).as_integer_ratio(), (2, 3))
         self.assertEqual(F(-4, 6).as_integer_ratio(), (-2, 3))
diff --git a/Misc/NEWS.d/next/Library/2022-12-24-04-13-54.gh-issue-100488.Ut8HbE.rst b/Misc/NEWS.d/next/Library/2022-12-24-04-13-54.gh-issue-100488.Ut8HbE.rst
new file mode 100644
index 000000000000..f7c07c0ab4c2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-12-24-04-13-54.gh-issue-100488.Ut8HbE.rst
@@ -0,0 +1 @@
+Add :meth:`Fraction.is_integer` to check whether a :class:`fractions.Fraction` is an integer. This improves duck type compatibility with :class:`float` and :class:`int`.