Add a custom __str__ method to KeyError that applies repr() to the
missing key. (Also added a guard to SyntaxError__str__ to prevent
calling PyString_Check(NULL).)
diff --git a/Lib/test/output/test_exceptions b/Lib/test/output/test_exceptions
index e1e146a..28a7aa8 100644
--- a/Lib/test/output/test_exceptions
+++ b/Lib/test/output/test_exceptions
@@ -10,7 +10,7 @@
ImportError
spam
IndexError
-spam
+'spam'
KeyError
spam
KeyboardInterrupt
diff --git a/Python/exceptions.c b/Python/exceptions.c
index 24ea25d..3f07089 100644
--- a/Python/exceptions.c
+++ b/Python/exceptions.c
@@ -785,7 +785,7 @@
/* XXX -- do all the additional formatting with filename and
lineno here */
- if (PyString_Check(str)) {
+ if (str != NULL && PyString_Check(str)) {
int have_filename = 0;
int have_lineno = 0;
char *buffer = NULL;
@@ -844,6 +844,44 @@
};
+static PyObject *
+KeyError__str__(PyObject *self, PyObject *args)
+{
+ PyObject *argsattr;
+ PyObject *result;
+
+ if (!PyArg_ParseTuple(args, "O:__str__", &self))
+ return NULL;
+
+ if (!(argsattr = PyObject_GetAttrString(self, "args")))
+ return NULL;
+
+ /* If args is a tuple of exactly one item, apply repr to args[0].
+ This is done so that e.g. the exception raised by {}[''] prints
+ KeyError: ''
+ rather than the confusing
+ KeyError
+ alone. The downside is that if KeyError is raised with an explanatory
+ string, that string will be displayed in quotes. Too bad.
+ If args is anything else, use the default Exception__str__().
+ */
+ if (PyTuple_Check(argsattr) && PyTuple_GET_SIZE(argsattr) == 1) {
+ PyObject *key = PyTuple_GET_ITEM(argsattr, 0);
+ result = PyObject_Repr(key);
+ }
+ else
+ result = Exception__str__(self, args);
+
+ Py_DECREF(argsattr);
+ return result;
+}
+
+static PyMethodDef KeyError_methods[] = {
+ {"__str__", KeyError__str__, METH_VARARGS},
+ {NULL, NULL}
+};
+
+
static
int get_int(PyObject *exc, const char *name, int *value)
{
@@ -1617,7 +1655,7 @@
{"IndexError", &PyExc_IndexError, &PyExc_LookupError,
IndexError__doc__},
{"KeyError", &PyExc_KeyError, &PyExc_LookupError,
- KeyError__doc__},
+ KeyError__doc__, KeyError_methods},
{"ArithmeticError", &PyExc_ArithmeticError, 0, ArithmeticError__doc__},
{"OverflowError", &PyExc_OverflowError, &PyExc_ArithmeticError,
OverflowError__doc__},