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gh-102778: Add sys.last_exc, deprecate sys.last_type, sys.last_value,sys.last_traceback (#102779)

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Irit Katriel 2023-03-18 11:47:11 +00:00 committed by GitHub
parent 039714d00f
commit e1e9bab006
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22 changed files with 103 additions and 36 deletions
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25
Doc/library/sys.rst
View file

@ -1102,22 +1102,25 @@ always available.
.. versionadded:: 3.5
.. data:: last_exc
This variable is not always defined; it is set to the exception instance
when an exception is not handled and the interpreter prints an error message
and a stack traceback. Its intended use is to allow an interactive user to
import a debugger module and engage in post-mortem debugging without having
to re-execute the command that caused the error. (Typical use is
``import pdb; pdb.pm()`` to enter the post-mortem debugger; see :mod:`pdb`
module for more information.)
.. versionadded:: 3.12
.. data:: last_type
last_value
last_traceback
These three variables are not always defined; they are set when an exception is
not handled and the interpreter prints an error message and a stack traceback.
Their intended use is to allow an interactive user to import a debugger module
and engage in post-mortem debugging without having to re-execute the command
that caused the error. (Typical use is ``import pdb; pdb.pm()`` to enter the
post-mortem debugger; see :mod:`pdb` module for
more information.)
The meaning of the variables is the same as that of the return values from
:func:`exc_info` above.
These three variables are deprecated; use :data:`sys.last_exc` instead.
They hold the legacy representation of ``sys.last_exc``, as returned
from :func:`exc_info` above.
.. data:: maxsize

10
Doc/whatsnew/3.12.rst
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@ -397,6 +397,12 @@ sys
with contributions from Gregory P. Smith [Google] and Mark Shannon
in :gh:`96123`.)
* Add :data:`sys.last_exc` which holds the last unhandled exception that
was raised (for post-mortem debugging use cases). Deprecate the
three fields that have the same information in its legacy form:
:data:`sys.last_type`, :data:`sys.last_value` and :data:`sys.last_traceback`.
(Contributed by Irit Katriel in :gh:`102778`.)
Optimizations
=============
@ -488,6 +494,10 @@ Deprecated
contain the creation time, which is also available in the new ``st_birthtime``
field. (Contributed by Steve Dower in :gh:`99726`.)
* The :data:`sys.last_type`, :data:`sys.last_value` and :data:`sys.last_traceback`
fields are deprecated. Use :data:`sys.last_exc` instead.
(Contributed by Irit Katriel in :gh:`102778`.)
Pending Removal in Python 3.13
------------------------------

1
Include/internal/pycore_global_objects_fini_generated.h generated
View file

@ -995,6 +995,7 @@ _PyStaticObjects_CheckRefcnt(PyInterpreterState *interp) {
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(kw2));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(lambda));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(last));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(last_exc));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(last_node));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(last_traceback));
_PyStaticObject_CheckRefcnt((PyObject *)&_Py_ID(last_type));

1
Include/internal/pycore_global_strings.h
View file

@ -481,6 +481,7 @@ struct _Py_global_strings {
STRUCT_FOR_ID(kw2)
STRUCT_FOR_ID(lambda)
STRUCT_FOR_ID(last)
STRUCT_FOR_ID(last_exc)
STRUCT_FOR_ID(last_node)
STRUCT_FOR_ID(last_traceback)
STRUCT_FOR_ID(last_type)

1
Include/internal/pycore_runtime_init_generated.h generated
View file

@ -987,6 +987,7 @@ extern "C" {
INIT_ID(kw2), \
INIT_ID(lambda), \
INIT_ID(last), \
INIT_ID(last_exc), \
INIT_ID(last_node), \
INIT_ID(last_traceback), \
INIT_ID(last_type), \

3
Include/internal/pycore_unicodeobject_generated.h generated
View file

@ -1296,6 +1296,9 @@ _PyUnicode_InitStaticStrings(void) {
string = &_Py_ID(last);
assert(_PyUnicode_CheckConsistency(string, 1));
PyUnicode_InternInPlace(&string);
string = &_Py_ID(last_exc);
assert(_PyUnicode_CheckConsistency(string, 1));
PyUnicode_InternInPlace(&string);
string = &_Py_ID(last_node);
assert(_PyUnicode_CheckConsistency(string, 1));
PyUnicode_InternInPlace(&string);

4
Lib/code.py
View file

@ -106,6 +106,7 @@ def showsyntaxerror(self, filename=None):
"""
type, value, tb = sys.exc_info()
sys.last_exc = value
sys.last_type = type
sys.last_value = value
sys.last_traceback = tb
@ -119,7 +120,7 @@ def showsyntaxerror(self, filename=None):
else:
# Stuff in the right filename
value = SyntaxError(msg, (filename, lineno, offset, line))
sys.last_value = value
sys.last_exc = sys.last_value = value
if sys.excepthook is sys.__excepthook__:
lines = traceback.format_exception_only(type, value)
self.write(''.join(lines))
@ -138,6 +139,7 @@ def showtraceback(self):
"""
sys.last_type, sys.last_value, last_tb = ei = sys.exc_info()
sys.last_traceback = last_tb
sys.last_exc = ei[1]
try:
lines = traceback.format_exception(ei[0], ei[1], last_tb.tb_next)
if sys.excepthook is sys.__excepthook__:

5
Lib/dis.py
View file

@ -118,7 +118,10 @@ def distb(tb=None, *, file=None, show_caches=False, adaptive=False):
"""Disassemble a traceback (default: last traceback)."""
if tb is None:
try:
tb = sys.last_traceback
if hasattr(sys, 'last_exc'):
tb = sys.last_exc.__traceback__
else:
tb = sys.last_traceback
except AttributeError:
raise RuntimeError("no last traceback to disassemble") from None
while tb.tb_next: tb = tb.tb_next

3
Lib/idlelib/idle_test/test_stackviewer.py
View file

@ -19,6 +19,7 @@ def setUpClass(cls):
except NameError:
svs.last_type, svs.last_value, svs.last_traceback = (
sys.exc_info())
svs.last_exc = svs.last_value
requires('gui')
cls.root = Tk()
@ -27,7 +28,7 @@ def setUpClass(cls):
@classmethod
def tearDownClass(cls):
svs = stackviewer.sys
del svs.last_traceback, svs.last_type, svs.last_value
del svs.last_exc, svs.last_traceback, svs.last_type, svs.last_value
cls.root.update_idletasks()
## for id in cls.root.tk.call('after', 'info'):

7
Lib/idlelib/pyshell.py
View file

@ -1367,11 +1367,14 @@ def open_stack_viewer(self, event=None):
if self.interp.rpcclt:
return self.interp.remote_stack_viewer()
try:
sys.last_traceback
if hasattr(sys, 'last_exc'):
sys.last_exc.__traceback__
else:
sys.last_traceback
except:
messagebox.showerror("No stack trace",
"There is no stack trace yet.\n"
"(sys.last_traceback is not defined)",
"(sys.last_exc and sys.last_traceback are not defined)",
parent=self.text)
return
from idlelib.stackviewer import StackBrowser

2
Lib/idlelib/run.py
View file

@ -239,6 +239,7 @@ def print_exception():
efile = sys.stderr
typ, val, tb = excinfo = sys.exc_info()
sys.last_type, sys.last_value, sys.last_traceback = excinfo
sys.last_exc = val
seen = set()
def print_exc(typ, exc, tb):
@ -629,6 +630,7 @@ def stackviewer(self, flist_oid=None):
flist = self.rpchandler.get_remote_proxy(flist_oid)
while tb and tb.tb_frame.f_globals["__name__"] in ["rpc", "run"]:
tb = tb.tb_next
sys.last_exc = val
sys.last_type = typ
sys.last_value = val
item = stackviewer.StackTreeItem(flist, tb)

21
Lib/idlelib/stackviewer.py
View file

@ -27,7 +27,10 @@ def __init__(self, flist=None, tb=None):
def get_stack(self, tb):
if tb is None:
tb = sys.last_traceback
if hasattr(sys, 'last_exc'):
tb = sys.last_exc.__traceback__
else:
tb = sys.last_traceback
stack = []
if tb and tb.tb_frame is None:
tb = tb.tb_next
@ -37,11 +40,15 @@ def get_stack(self, tb):
return stack
def get_exception(self):
type = sys.last_type
value = sys.last_value
if hasattr(type, "__name__"):
type = type.__name__
s = str(type)
if hasattr(sys, 'last_exc'):
typ = type(sys.last_exc)
value = sys.last_exc
else:
typ = sys.last_type
value = sys.last_value
if hasattr(typ, "__name__"):
typ = typ.__name__
s = str(typ)
if value is not None:
s = s + ": " + str(value)
return s
@ -136,6 +143,7 @@ def _stack_viewer(parent): # htest #
except NameError:
exc_type, exc_value, exc_tb = sys.exc_info()
# inject stack trace to sys
sys.last_exc = exc_value
sys.last_type = exc_type
sys.last_value = exc_value
sys.last_traceback = exc_tb
@ -143,6 +151,7 @@ def _stack_viewer(parent): # htest #
StackBrowser(top, flist=flist, top=top, tb=exc_tb)
# restore sys to original state
del sys.last_exc
del sys.last_type
del sys.last_value
del sys.last_traceback

6
Lib/pdb.py
View file

@ -1739,7 +1739,11 @@ def post_mortem(t=None):
def pm():
"""Enter post-mortem debugging of the traceback found in sys.last_traceback."""
post_mortem(sys.last_traceback)
if hasattr(sys, 'last_exc'):
tb = sys.last_exc.__traceback__
else:
tb = sys.last_traceback
post_mortem(tb)
# Main program for testing

4
Lib/pydoc_data/topics.py
View file

@ -4799,7 +4799,7 @@
'pdb.pm()\n'
'\n'
' Enter post-mortem debugging of the traceback found in\n'
' "sys.last_traceback".\n'
' "sys.last_exc".\n'
'\n'
'The "run*" functions and "set_trace()" are aliases for '
'instantiating\n'
@ -13858,7 +13858,7 @@
'if\n'
' the interpreter is interactive, it is also made available to '
'the\n'
' user as "sys.last_traceback".\n'
' user as "sys.last_exc".\n'
'\n'
' For explicitly created tracebacks, it is up to the creator '
'of\n'

10
Lib/test/test_dis.py
View file

@ -1026,6 +1026,10 @@ def test_disassemble_try_finally(self):
self.do_disassembly_test(_tryfinallyconst, dis_tryfinallyconst)
def test_dis_none(self):
try:
del sys.last_exc
except AttributeError:
pass
try:
del sys.last_traceback
except AttributeError:
@ -1043,7 +1047,7 @@ def test_dis_traceback(self):
1/0
except Exception as e:
tb = e.__traceback__
sys.last_traceback = tb
sys.last_exc = e
tb_dis = self.get_disassemble_as_string(tb.tb_frame.f_code, tb.tb_lasti)
self.do_disassembly_test(None, tb_dis, True)
@ -1900,6 +1904,10 @@ def test_findlabels(self):
class TestDisTraceback(DisTestBase):
def setUp(self) -> None:
try: # We need to clean up existing tracebacks
del sys.last_exc
except AttributeError:
pass
try: # We need to clean up existing tracebacks
del sys.last_traceback
except AttributeError:

4
Lib/test/test_ttk/test_extensions.py
View file

@ -45,7 +45,9 @@ def test_widget_destroy(self):
# value which causes the tracing callback to be called and then
# it tries calling instance attributes not yet defined.
ttk.LabeledScale(self.root, variable=myvar)
if hasattr(sys, 'last_type'):
if hasattr(sys, 'last_exc'):
self.assertNotEqual(type(sys.last_exc), tkinter.TclError)
elif hasattr(sys, 'last_type'):
self.assertNotEqual(sys.last_type, tkinter.TclError)
def test_initialization(self):

1
Lib/tkinter/__init__.py
View file

@ -2400,6 +2400,7 @@ def report_callback_exception(self, exc, val, tb):
should when sys.stderr is None."""
import traceback
print("Exception in Tkinter callback", file=sys.stderr)
sys.last_exc = val
sys.last_type = exc
sys.last_value = val
sys.last_traceback = tb

16
Lib/traceback.py
View file

@ -179,7 +179,7 @@ def _safe_string(value, what, func=str):
# --
def print_exc(limit=None, file=None, chain=True):
"""Shorthand for 'print_exception(*sys.exc_info(), limit, file)'."""
"""Shorthand for 'print_exception(*sys.exc_info(), limit, file, chain)'."""
print_exception(*sys.exc_info(), limit=limit, file=file, chain=chain)
def format_exc(limit=None, chain=True):
@ -187,12 +187,16 @@ def format_exc(limit=None, chain=True):
return "".join(format_exception(*sys.exc_info(), limit=limit, chain=chain))
def print_last(limit=None, file=None, chain=True):
"""This is a shorthand for 'print_exception(sys.last_type,
sys.last_value, sys.last_traceback, limit, file)'."""
if not hasattr(sys, "last_type"):
"""This is a shorthand for 'print_exception(sys.last_exc, limit, file, chain)'."""
if not hasattr(sys, "last_exc") and not hasattr(sys, "last_type"):
raise ValueError("no last exception")
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
limit, file, chain)
if hasattr(sys, "last_exc"):
print_exception(sys.last_exc, limit, file, chain)
else:
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
limit, file, chain)
#
# Printing and Extracting Stacks.

3
Misc/NEWS.d/next/Core and Builtins/2023-03-17-13-43-34.gh-issue-102778.ANDv8I.rst Normal file
View file

@ -0,0 +1,3 @@
Add :data:`sys.last_exc` and deprecate :data:`sys.last_type`, :data:`sys.last_value`
and :data:`sys.last_traceback`,
which hold the same information in its legacy form.

2
Python/pylifecycle.c
View file

@ -1304,7 +1304,7 @@ finalize_modules_delete_special(PyThreadState *tstate, int verbose)
{
// List of names to clear in sys
static const char * const sys_deletes[] = {
"path", "argv", "ps1", "ps2",
"path", "argv", "ps1", "ps2", "last_exc",
"last_type", "last_value", "last_traceback",
"__interactivehook__",
// path_hooks and path_importer_cache are cleared

4
Python/pythonrun.c
View file

@ -776,6 +776,10 @@ _PyErr_PrintEx(PyThreadState *tstate, int set_sys_last_vars)
}
if (set_sys_last_vars) {
if (_PySys_SetAttr(&_Py_ID(last_exc), exc) < 0) {
_PyErr_Clear(tstate);
}
/* Legacy version: */
if (_PySys_SetAttr(&_Py_ID(last_type), typ) < 0) {
_PyErr_Clear(tstate);
}

6
Python/sysmodule.c
View file

@ -2670,11 +2670,13 @@ stderr -- standard error object; used for error messages\n\
By assigning other file objects (or objects that behave like files)\n\
to these, it is possible to redirect all of the interpreter's I/O.\n\
\n\
last_exc - the last uncaught exception\n\
Only available in an interactive session after a\n\
traceback has been printed.\n\
last_type -- type of last uncaught exception\n\
last_value -- value of last uncaught exception\n\
last_traceback -- traceback of last uncaught exception\n\
These three are only available in an interactive session after a\n\
traceback has been printed.\n\
These three are the (deprecated) legacy representation of last_exc.\n\
"
)
/* concatenating string here */