gh-84978: expose __float__ dunder method as as_float

Doc/library/operator.rst

@@ -116,6 +116,10 @@ The mathematical and bitwise operations are the most numerous:
       The result always has exact type :class:`int`.  Previously, the result
       could have been an instance of a subclass of ``int``.
 
+.. function:: as_float(a)
+              __float__(a)
+
+   Return *a* converted to a float.  Equivalent to ``a.__float__()``.
 
 .. function:: inv(obj)
               invert(obj)

Lib/operator.py

@@ -10,7 +10,7 @@
 This is the pure Python implementation of the module.
 """
 
-__all__ = ['abs', 'add', 'and_', 'attrgetter', 'call', 'concat', 'contains', 'countOf',
+__all__ = ['abs', 'add', 'and_', 'attrgetter', 'as_float', 'call', 'concat', 'contains', 'countOf',
            'delitem', 'eq', 'floordiv', 'ge', 'getitem', 'gt', 'iadd', 'iand',
            'iconcat', 'ifloordiv', 'ilshift', 'imatmul', 'imod', 'imul',
            'index', 'indexOf', 'inv', 'invert', 'ior', 'ipow', 'irshift',
@@ -88,6 +88,10 @@ def index(a):
     "Same as a.__index__()."
     return a.__index__()
 
+def as_float(a):
+    "Same as a.__float__()."
+    return a.__float__()
+
 def inv(a):
     "Same as ~a."
     return ~a
@@ -432,6 +436,7 @@ def ixor(a, b):
 __call__ = call
 __floordiv__ = floordiv
 __index__ = index
+__float__ = as_float
 __inv__ = inv
 __invert__ = invert
 __lshift__ = lshift

Lib/test/test_operator.py

@@ -142,6 +142,14 @@ def test_add(self):
         self.assertRaises(TypeError, operator.add, None, None)
         self.assertEqual(operator.add(3, 4), 7)
 
+    def test_as_float(self):
+        from fractions import Fraction as F
+
+        operator = self.module
+        self.assertRaises(TypeError, operator.as_float)
+        self.assertRaises(AttributeError, operator.as_float, None)
+        self.assertEqual(operator.as_float(F(1, 2)), 0.5)
+
     def test_bitwise_and(self):
         operator = self.module
         self.assertRaises(TypeError, operator.and_)

Misc/NEWS.d/next/Library/2023-10-06-09-36-06.gh-issue-84978.WVF04J.rst

@@ -0,0 +1,2 @@
+Expose :meth:`~object.__float__` as :func:`operator.as_float`.  Patch by
+Sergey B Kirpichev.