Issue 3188: accept float('infinity') as well as float('inf'). This

makes the float constructor behave in the same way as specified
by various other language standards, including C99, IEEE 754r,
and the IBM Decimal standard.

Lib/test/test_float.py

@@ -253,24 +253,36 @@ class ReprTestCase(unittest.TestCase):
         floats_file.close()
 
 # Beginning with Python 2.6 float has cross platform compatible
-# ways to create and representate inf and nan
+# ways to create and represent inf and nan
 class InfNanTest(unittest.TestCase):
     def test_inf_from_str(self):
         self.assert_(isinf(float("inf")))
         self.assert_(isinf(float("+inf")))
         self.assert_(isinf(float("-inf")))
+        self.assert_(isinf(float("infinity")))
+        self.assert_(isinf(float("+infinity")))
+        self.assert_(isinf(float("-infinity")))
 
         self.assertEqual(repr(float("inf")), "inf")
         self.assertEqual(repr(float("+inf")), "inf")
         self.assertEqual(repr(float("-inf")), "-inf")
+        self.assertEqual(repr(float("infinity")), "inf")
+        self.assertEqual(repr(float("+infinity")), "inf")
+        self.assertEqual(repr(float("-infinity")), "-inf")
 
         self.assertEqual(repr(float("INF")), "inf")
         self.assertEqual(repr(float("+Inf")), "inf")
         self.assertEqual(repr(float("-iNF")), "-inf")
+        self.assertEqual(repr(float("Infinity")), "inf")
+        self.assertEqual(repr(float("+iNfInItY")), "inf")
+        self.assertEqual(repr(float("-INFINITY")), "-inf")
 
         self.assertEqual(str(float("inf")), "inf")
         self.assertEqual(str(float("+inf")), "inf")
         self.assertEqual(str(float("-inf")), "-inf")
+        self.assertEqual(str(float("infinity")), "inf")
+        self.assertEqual(str(float("+infinity")), "inf")
+        self.assertEqual(str(float("-infinity")), "-inf")
 
         self.assertRaises(ValueError, float, "info")
         self.assertRaises(ValueError, float, "+info")
@@ -278,6 +290,10 @@ class InfNanTest(unittest.TestCase):
         self.assertRaises(ValueError, float, "in")
         self.assertRaises(ValueError, float, "+in")
         self.assertRaises(ValueError, float, "-in")
+        self.assertRaises(ValueError, float, "infinit")
+        self.assertRaises(ValueError, float, "+Infin")
+        self.assertRaises(ValueError, float, "-INFI")
+        self.assertRaises(ValueError, float, "infinitys")
 
     def test_inf_as_str(self):
         self.assertEqual(repr(1e300 * 1e300), "inf")

Objects/floatobject.c

@@ -246,6 +246,9 @@ PyFloat_FromString(PyObject *v, char **pend)
 		if (PyOS_strnicmp(p, "inf", 4) == 0) {
 			Py_RETURN_INF(sign);
 		}
+		if (PyOS_strnicmp(p, "infinity", 9) == 0) {
+			Py_RETURN_INF(sign);
+		}
 #ifdef Py_NAN
 		if(PyOS_strnicmp(p, "nan", 4) == 0) {
 			Py_RETURN_NAN;