python · erlend-aasland · Jan 9, 2024 · Jan 23, 2022 · Apr 3, 2023 · Jan 6, 2024
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
@@ -174,6 +174,16 @@ def testRepr(self):
        self.assertEqual(repr(self.f),
                         "<%s.FileIO [closed]>" % (self.modulename,))

+    def test_subclass_repr(self):
+        class TestSubclass(self.FileIO):
+            pass
+
+        f = TestSubclass(TESTFN)
+        with f:
+            self.assertIn(TestSubclass.__name__, repr(f))
+
+        self.assertIn(TestSubclass.__name__, repr(f))
+
    def testReprNoCloseFD(self):
        fd = os.open(TESTFN, os.O_RDONLY)
        try:

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
@@ -2806,6 +2806,13 @@ def test_recursive_repr(self):
            with self.assertRaises(RuntimeError):
                repr(t)  # Should not crash

+    def test_subclass_repr(self):
+        class TestSubclass(self.TextIOWrapper):
+            pass
+
+        f = TestSubclass(self.StringIO())
+        self.assertIn(TestSubclass.__name__, repr(f))
+
    def test_line_buffering(self):
        r = self.BytesIO()
        b = self.BufferedWriter(r, 1000)

diff --git a/Lib/test/test_winconsoleio.py b/Lib/test/test_winconsoleio.py
@@ -98,6 +98,16 @@ def test_open_name(self):
            self.assertIsInstance(f, ConIO)
            f.close()

+    def test_subclass_repr(self):
+        class TestSubclass(ConIO):
+            pass
+
+        f = TestSubclass("CON")
+        with f:
+            self.assertIn(TestSubclass.__name__, repr(f))
+
+        self.assertIn(TestSubclass.__name__, repr(f))
+
    @unittest.skipIf(sys.getwindowsversion()[:2] <= (6, 1),
        "test does not work on Windows 7 and earlier")
    def test_conin_conout_names(self):

diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-01-23-18-00-10.bpo-21861.N8E1zw.rst b/Misc/NEWS.d/next/Core and Builtins/2022-01-23-18-00-10.bpo-21861.N8E1zw.rst
@@ -0,0 +1,3 @@
+Use the object's actual class name in :meth:`_io.FileIO.__repr__`,
+:meth:`_io._WindowsConsoleIO` and :meth:`_io.TextIOWrapper.__repr__`, to
+make these methods subclass friendly.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
@@ -1100,31 +1100,32 @@ static PyObject *
 fileio_repr(fileio *self)
 {
    PyObject *nameobj, *res;
+    const char *type_name = Py_TYPE((PyObject *) self)->tp_name;

-    if (self->fd < 0)
-        return PyUnicode_FromFormat("<_io.FileIO [closed]>");
+    if (self->fd < 0) {
+        return PyUnicode_FromFormat("<%.100s [closed]>", type_name);
+    }

    if (PyObject_GetOptionalAttr((PyObject *) self, &_Py_ID(name), &nameobj) < 0) {
        return NULL;
    }
    if (nameobj == NULL) {
        res = PyUnicode_FromFormat(
-            "<_io.FileIO fd=%d mode='%s' closefd=%s>",
-            self->fd, mode_string(self), self->closefd ? "True" : "False");
+            "<%.100s fd=%d mode='%s' closefd=%s>",
+            type_name, self->fd, mode_string(self), self->closefd ? "True" : "False");
    }
    else {
        int status = Py_ReprEnter((PyObject *)self);
        res = NULL;
        if (status == 0) {
            res = PyUnicode_FromFormat(
-                "<_io.FileIO name=%R mode='%s' closefd=%s>",
-                nameobj, mode_string(self), self->closefd ? "True" : "False");
+                "<%.100s name=%R mode='%s' closefd=%s>",
+                type_name, nameobj, mode_string(self), self->closefd ? "True" : "False");
            Py_ReprLeave((PyObject *)self);
        }
        else if (status > 0) {
            PyErr_Format(PyExc_RuntimeError,
-                         "reentrant call inside %s.__repr__",
-                         Py_TYPE(self)->tp_name);
+                         "reentrant call inside %.100s.__repr__", type_name);
        }
        Py_DECREF(nameobj);
    }

diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
@@ -2944,19 +2944,20 @@ textiowrapper_repr(textio *self)
 {
    PyObject *nameobj, *modeobj, *res, *s;
    int status;
+    const char *type_name = Py_TYPE(self)->tp_name;

    CHECK_INITIALIZED(self);

-    res = PyUnicode_FromString("<_io.TextIOWrapper");
+    res = PyUnicode_FromFormat("<%.100s", type_name);
    if (res == NULL)
        return NULL;

    status = Py_ReprEnter((PyObject *)self);
    if (status != 0) {
        if (status > 0) {
            PyErr_Format(PyExc_RuntimeError,
-                         "reentrant call inside %s.__repr__",
-                         Py_TYPE(self)->tp_name);
+                         "reentrant call inside %.100s.__repr__",
+                         type_name);
        }
        goto error;
    }

diff --git a/Modules/_io/winconsoleio.c b/Modules/_io/winconsoleio.c
@@ -1070,15 +1070,22 @@ _io__WindowsConsoleIO_write_impl(winconsoleio *self, PyTypeObject *cls,
 static PyObject *
 winconsoleio_repr(winconsoleio *self)
 {
-    if (self->fd == -1)
-        return PyUnicode_FromFormat("<_io._WindowsConsoleIO [closed]>");
-
-    if (self->readable)
-        return PyUnicode_FromFormat("<_io._WindowsConsoleIO mode='rb' closefd=%s>",
-            self->closefd ? "True" : "False");
-    if (self->writable)
-        return PyUnicode_FromFormat("<_io._WindowsConsoleIO mode='wb' closefd=%s>",
-            self->closefd ? "True" : "False");
+    const char *type_name = (Py_TYPE((PyObject *)self)->tp_name);
+
+    if (self->fd == -1) {
+        return PyUnicode_FromFormat("<%.100s [closed]>", type_name);
+    }
+
+    if (self->readable) {
+        return PyUnicode_FromFormat("<%.100s mode='rb' closefd=%s>",
+                                    type_name,
+                                    self->closefd ? "True" : "False");
+    }
+    if (self->writable) {
+        return PyUnicode_FromFormat("<%.100s mode='wb' closefd=%s>",
+                                    type_name,
+                                    self->closefd ? "True" : "False");
+    }

    PyErr_SetString(PyExc_SystemError, "_WindowsConsoleIO has invalid mode");
    return NULL;