bpo-37645: simplify __str__ of function objects

Lib/test/test_asyncio/test_events.py

@@ -2155,11 +2155,10 @@ def test_handle_repr(self):
             filename, lineno = test_utils.get_function_source(method)
             h = asyncio.Handle(cb, (), self.loop)
 
-            cb_regex = r'<function HandleTests.test_handle_repr .*>'
-            cb_regex = (r'functools.partialmethod\(%s, , \)\(\)' % cb_regex)
-            regex = (r'^<Handle %s at %s:%s>$'
-                     % (cb_regex, re.escape(filename), lineno))
-            self.assertRegex(repr(h), regex)
+            cb_repr = "HandleTests.test_handle_repr()"
+            cb_repr = f"functools.partialmethod({cb_repr}, , )()"
+            expected = f"<Handle {cb_repr} at {filename}:{lineno}>"
+            self.assertEqual(repr(h), expected)
 
     def test_handle_repr_debug(self):
         self.loop.get_debug.return_value = True

Lib/test/test_call.py

@@ -609,5 +609,15 @@ def __call__(self, *args):
                 self.assertEqual(expected, wrapped(*args, **kwargs))
 
 
+class TestReprStr(unittest.TestCase):
+    def test_function(self):
+        f = testfunction
+        self.assertEqual(str(f), "testfunction()")
+        self.assertRegex(repr(f), r"^<function testfunction at .*>$")
+        f = PythonClass.method
+        self.assertEqual(str(f), "PythonClass.method()")
+        self.assertRegex(repr(f), r"^<function PythonClass.method at .*>$")
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Core and Builtins/2019-08-14-22-35-30.bpo-37645.Nw3lbT.rst

@@ -0,0 +1,2 @@
+For a Python function ``f``, ``str(f)`` now returns ``f()`` instead of
+``<function f at 0x...>``

Objects/funcobject.c

@@ -605,6 +605,13 @@ func_repr(PyFunctionObject *op)
                                op->func_qualname, op);
 }
 
+static PyObject*
+func_str(PyFunctionObject *op)
+{
+    return PyUnicode_FromFormat("%U()", op->func_qualname);
+}
+
+
 static int
 func_traverse(PyFunctionObject *f, visitproc visit, void *arg)
 {
@@ -649,7 +656,7 @@ PyTypeObject PyFunction_Type = {
     0,                                          /* tp_as_mapping */
     0,                                          /* tp_hash */
     PyVectorcall_Call,                          /* tp_call */
-    0,                                          /* tp_str */
+    (reprfunc)func_str,                         /* tp_str */
     0,                                          /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */