Patch #1591665: implement the __dir__() special function lookup in PyObject_Dir.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 3c149e4..5d87744 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -427,15 +427,16 @@
PyDoc_STRVAR(dir_doc,
"dir([object]) -> list of strings\n"
"\n"
-"Return an alphabetized list of names comprising (some of) the attributes\n"
-"of the given object, and of attributes reachable from it:\n"
-"\n"
-"No argument: the names in the current scope.\n"
-"Module object: the module attributes.\n"
-"Type or class object: its attributes, and recursively the attributes of\n"
-" its bases.\n"
-"Otherwise: its attributes, its class's attributes, and recursively the\n"
-" attributes of its class's base classes.");
+"If called without an argument, return the names in the current scope.\n"
+"Else, return an alphabetized list of names comprising (some of) the attributes\n"
+"of the given object, and of attributes reachable from it.\n"
+"If the object supplies a method named __dir__, it will be used; otherwise\n"
+"the default dir() logic is used and returns:\n"
+" for a module object: the module's attributes.\n"
+" for a class object: its attributes, and recursively the attributes\n"
+" of its bases.\n"
+" for an other object: its attributes, its class's attributes, and\n"
+" recursively the attributes of its class's base classes.");
static PyObject *
builtin_divmod(PyObject *self, PyObject *args)