bpo-32468: Better frame repr() (#5067)

bpo-32468: Better frame repr()

Lib/test/test_frame.py

+import re
 import types
 import unittest
 import weakref
@@ -159,5 +160,45 @@ class FrameLocalsTest(unittest.TestCase):
         self.assertEqual(inner.f_locals, {})
 
 
+class ReprTest(unittest.TestCase):
+    """
+    Tests for repr(frame).
+    """
+
+    def test_repr(self):
+        def outer():
+            x = 5
+            y = 6
+            def inner():
+                z = x + 2
+                1/0
+                t = 9
+            return inner()
+
+        offset = outer.__code__.co_firstlineno
+        try:
+            outer()
+        except ZeroDivisionError as e:
+            tb = e.__traceback__
+            frames = []
+            while tb:
+                frames.append(tb.tb_frame)
+                tb = tb.tb_next
+        else:
+            self.fail("should have raised")
+
+        f_this, f_outer, f_inner = frames
+        file_repr = re.escape(repr(__file__))
+        self.assertRegex(repr(f_this),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code test_repr>$"
+                         % (file_repr, offset + 23))
+        self.assertRegex(repr(f_outer),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code outer>$"
+                         % (file_repr, offset + 7))
+        self.assertRegex(repr(f_inner),
+                         r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code inner>$"
+                         % (file_repr, offset + 5))
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2017-12-31-20-32-58.bpo-32468.YBs__0.rst

+Improve frame repr() to mention filename, code name and current line number.

Objects/frameobject.c

@@ -547,6 +547,15 @@ frame_sizeof(PyFrameObject *f)
 PyDoc_STRVAR(sizeof__doc__,
 "F.__sizeof__() -> size of F in memory, in bytes");
 
+static PyObject *
+frame_repr(PyFrameObject *f)
+{
+    int lineno = PyFrame_GetLineNumber(f);
+    return PyUnicode_FromFormat(
+        "<frame at %p, file %R, line %d, code %S>",
+        f, f->f_code->co_filename, lineno, f->f_code->co_name);
+}
+
 static PyMethodDef frame_methods[] = {
     {"clear",           (PyCFunction)frame_clear,       METH_NOARGS,
      clear__doc__},
@@ -565,7 +574,7 @@ PyTypeObject PyFrame_Type = {
     0,                                          /* tp_getattr */
     0,                                          /* tp_setattr */
     0,                                          /* tp_reserved */
-    0,                                          /* tp_repr */
+    (reprfunc)frame_repr,                       /* tp_repr */
     0,                                          /* tp_as_number */
     0,                                          /* tp_as_sequence */
     0,                                          /* tp_as_mapping */