bpo-33985: Implement ContextVar.name attribute. (GH-7980)

(cherry picked from commit 41cb0bae)
Co-authored-by: Yury Selivanov <yury@magic.io>

Doc/library/contextvars.rst

@@ -48,6 +48,8 @@ Context Variables
 
       The name of the variable.  This is a read-only property.
 
+      .. versionadded:: 3.7.1
+
    .. method:: get([default])
 
       Return a value for the context variable for the current context.

Lib/test/test_context.py

@@ -30,8 +30,13 @@ class ContextTest(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, 'must be a str'):
             contextvars.ContextVar(1)
 
-        c = contextvars.ContextVar('a')
-        self.assertNotEqual(hash(c), hash('a'))
+        c = contextvars.ContextVar('aaa')
+        self.assertEqual(c.name, 'aaa')
+
+        with self.assertRaises(AttributeError):
+            c.name = 'bbb'
+
+        self.assertNotEqual(hash(c), hash('aaa'))
 
     def test_context_var_new_2(self):
         self.assertIsNone(contextvars.ContextVar[int])

Misc/NEWS.d/next/Core and Builtins/2018-06-27-18-56-41.bpo-33985.ILJ3Af.rst

+Implement contextvars.ContextVar.name attribute.

Python/context.c

@@ -940,6 +940,10 @@ contextvar_cls_getitem(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
+static PyMemberDef PyContextVar_members[] = {
+    {"name", T_OBJECT, offsetof(PyContextVar, var_name), READONLY},
+    {NULL}
+};
 
 static PyMethodDef PyContextVar_methods[] = {
     _CONTEXTVARS_CONTEXTVAR_GET_METHODDEF
@@ -955,6 +959,7 @@ PyTypeObject PyContextVar_Type = {
     "ContextVar",
     sizeof(PyContextVar),
     .tp_methods = PyContextVar_methods,
+    .tp_members = PyContextVar_members,
     .tp_dealloc = (destructor)contextvar_tp_dealloc,
     .tp_getattro = PyObject_GenericGetAttr,
     .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,