Implicit exception chaining via __context__ (PEP 3134).

Patch 3108 by Antooine Pitrou.
This commit is contained in:
Guido van Rossum 2008-06-14 20:20:24 +00:00
parent 973124fd70
commit b4fb6e4d27
4 changed files with 139 additions and 33 deletions

View File

@ -480,7 +480,12 @@ class ExceptionTests(unittest.TestCase):
inner_raising_func()
except:
raise KeyError
except KeyError:
except KeyError as e:
# We want to test that the except block above got rid of
# the exception raised in inner_raising_func(), but it
# also ends up in the __context__ of the KeyError, so we
# must clear the latter manually for our test to succeed.
e.__context__ = None
obj = None
obj = wr()
self.failUnless(obj is None, "%s" % obj)

View File

@ -181,32 +181,102 @@ class TestTraceback(unittest.TestCase):
self.fail("No exception raised")
# Disabled until context is implemented
# class TestContext(object):
# def test_instance_context_bare_raise(self):
# context = IndexError()
# try:
# try:
# raise context
# except:
# raise OSError()
# except OSError as e:
# self.assertEqual(e.__context__, context)
# else:
# self.fail("No exception raised")
#
# def test_class_context_bare_raise(self):
# context = IndexError
# try:
# try:
# raise context
# except:
# raise OSError()
# except OSError as e:
# self.assertNotEqual(e.__context__, context)
# self.failUnless(isinstance(e.__context__, context))
# else:
# self.fail("No exception raised")
class TestContext(unittest.TestCase):
def test_instance_context_instance_raise(self):
context = IndexError()
try:
try:
raise context
except:
raise OSError()
except OSError as e:
self.assertEqual(e.__context__, context)
else:
self.fail("No exception raised")
def test_class_context_instance_raise(self):
context = IndexError
try:
try:
raise context
except:
raise OSError()
except OSError as e:
self.assertNotEqual(e.__context__, context)
self.failUnless(isinstance(e.__context__, context))
else:
self.fail("No exception raised")
def test_class_context_class_raise(self):
context = IndexError
try:
try:
raise context
except:
raise OSError
except OSError as e:
self.assertNotEqual(e.__context__, context)
self.failUnless(isinstance(e.__context__, context))
else:
self.fail("No exception raised")
def test_c_exception_context(self):
try:
try:
1/0
except:
raise OSError
except OSError as e:
self.failUnless(isinstance(e.__context__, ZeroDivisionError))
else:
self.fail("No exception raised")
def test_c_exception_raise(self):
try:
try:
1/0
except:
xyzzy
except NameError as e:
self.failUnless(isinstance(e.__context__, ZeroDivisionError))
else:
self.fail("No exception raised")
def test_noraise_finally(self):
try:
try:
pass
finally:
raise OSError
except OSError as e:
self.failUnless(e.__context__ is None)
else:
self.fail("No exception raised")
def test_raise_finally(self):
try:
try:
1/0
finally:
raise OSError
except OSError as e:
self.failUnless(isinstance(e.__context__, ZeroDivisionError))
else:
self.fail("No exception raised")
def test_context_manager(self):
class ContextManager:
def __enter__(self):
pass
def __exit__(self, t, v, tb):
xyzzy
try:
with ContextManager():
1/0
except NameError as e:
self.failUnless(isinstance(e.__context__, ZeroDivisionError))
else:
self.fail("No exception raised")
class TestRemovedFunctionality(unittest.TestCase):

View File

@ -2817,11 +2817,12 @@ fail: /* Jump here from prelude on failure */
static enum why_code
do_raise(PyObject *exc, PyObject *cause)
{
PyObject *type = NULL, *value = NULL, *tb = NULL;
PyObject *type = NULL, *value = NULL;
if (exc == NULL) {
/* Reraise */
PyThreadState *tstate = PyThreadState_GET();
PyObject *tb;
type = tstate->exc_type;
value = tstate->exc_value;
tb = tstate->exc_traceback;
@ -2862,7 +2863,6 @@ do_raise(PyObject *exc, PyObject *cause)
goto raise_error;
}
tb = PyException_GetTraceback(value);
if (cause) {
PyObject *fixed_cause;
if (PyExceptionClass_Check(cause)) {
@ -2883,13 +2883,15 @@ do_raise(PyObject *exc, PyObject *cause)
PyException_SetCause(value, fixed_cause);
}
PyErr_Restore(type, value, tb);
PyErr_SetObject(type, value);
/* PyErr_SetObject incref's its arguments */
Py_XDECREF(value);
Py_XDECREF(type);
return WHY_EXCEPTION;
raise_error:
Py_XDECREF(value);
Py_XDECREF(type);
Py_XDECREF(tb);
Py_XDECREF(cause);
return WHY_EXCEPTION;
}

View File

@ -52,6 +52,9 @@ PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)
void
PyErr_SetObject(PyObject *exception, PyObject *value)
{
PyThreadState *tstate = PyThreadState_GET();
PyObject *tb = NULL;
if (exception != NULL &&
!PyExceptionClass_Check(exception)) {
PyErr_Format(PyExc_SystemError,
@ -59,9 +62,35 @@ PyErr_SetObject(PyObject *exception, PyObject *value)
exception);
return;
}
Py_XINCREF(exception);
Py_XINCREF(value);
PyErr_Restore(exception, value, (PyObject *)NULL);
if (tstate->exc_value != NULL && tstate->exc_value != Py_None) {
/* Implicit exception chaining */
if (value == NULL || !PyExceptionInstance_Check(value)) {
/* We must normalize the value right now */
PyObject *args, *fixed_value;
if (value == NULL || value == Py_None)
args = PyTuple_New(0);
else if (PyTuple_Check(value)) {
Py_INCREF(value);
args = value;
}
else
args = PyTuple_Pack(1, value);
fixed_value = args ?
PyEval_CallObject(exception, args) : NULL;
Py_XDECREF(args);
Py_XDECREF(value);
if (fixed_value == NULL)
return;
value = fixed_value;
}
Py_INCREF(tstate->exc_value);
PyException_SetContext(value, tstate->exc_value);
}
if (value != NULL && PyExceptionInstance_Check(value))
tb = PyException_GetTraceback(value);
Py_XINCREF(exception);
PyErr_Restore(exception, value, tb);
}
void