Add sys.excepthook.
Update docstring and library reference section on 'sys' module.
New API PyErr_Display, just for displaying errors, called by excepthook.
Uncaught exceptions now call sys.excepthook; if that fails, we fall back
to calling PyErr_Display directly.
Also comes with sys.__excepthook__ and sys.__displayhook__.
diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index df32182..44b7853 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -48,11 +48,32 @@
If \var{value} is not \code{None}, this function prints it to
\code{sys.stdout}, and saves it in \code{__builtin__._}.
-This function is called when an expression is entered at the prompt
-of an interactive Python session. It exists mainly so it can be
-overridden.
+\code{sys.displayhook} is called on the result of evaluating
+an expression entered in an interactive Python session.
+The display of these values can be customized by assigning
+another function to \code{sys.displayhook}.
\end{funcdesc}
+\begin{funcdesc}{excepthook}{\var{type}, \var{value}, \var{traceback}}
+This function prints out a given traceback and exception to
+\code{sys.stderr}.
+
+\code{sys.excepthook} is called when an exception is raised
+and uncaught. In an interactive session this happens just before
+control is returned to the prompt; in a Python program this happens
+just before the program exits.
+The handling of such top-level exceptions can be customized by
+assigning another function to \code{sys.excepthook}.
+\end{funcdesc}
+
+\begin{datadesc}{__displayhook__}
+\dataline{__excepthook__}
+These objects contain the original values of \code{displayhook}
+and \code{excepthook} at the start of the program. They are saved
+so that \code{displayhook} and \code{excepthook} can be restored
+in case they happen to get replaced with broken objects.
+\end{datadesc}
+
\begin{funcdesc}{exc_info}{}
This function returns a tuple of three values that give information
about the exception that is currently being handled. The information
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index c2aa207..e7274ec 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -59,6 +59,7 @@
DL_IMPORT(void) PyErr_Print(void);
DL_IMPORT(void) PyErr_PrintEx(int);
+DL_IMPORT(void) PyErr_Display(PyObject *, PyObject *, PyObject *);
DL_IMPORT(int) Py_AtExit(void (*func)(void));
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index edb8a11..6fa85ac 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -801,8 +801,7 @@
void
PyErr_PrintEx(int set_sys_last_vars)
{
- int err = 0;
- PyObject *exception, *v, *tb, *f;
+ PyObject *exception, *v, *tb, *hook;
PyErr_Fetch(&exception, &v, &tb);
PyErr_NormalizeException(&exception, &v, &tb);
@@ -845,14 +844,47 @@
PySys_SetObject("last_value", v);
PySys_SetObject("last_traceback", tb);
}
- f = PySys_GetObject("stderr");
+ hook = PySys_GetObject("excepthook");
+ if (hook) {
+ PyObject *args = Py_BuildValue("(OOO)",
+ exception, v ? v : Py_None, tb ? tb : Py_None);
+ PyObject *result = PyEval_CallObject(hook, args);
+ if (result == NULL) {
+ PyObject *exception2, *v2, *tb2;
+ PyErr_Fetch(&exception2, &v2, &tb2);
+ PyErr_NormalizeException(&exception2, &v2, &tb2);
+ if (Py_FlushLine())
+ PyErr_Clear();
+ fflush(stdout);
+ PySys_WriteStderr("Error in sys.excepthook:\n");
+ PyErr_Display(exception2, v2, tb2);
+ PySys_WriteStderr("\nOriginal exception was:\n");
+ PyErr_Display(exception, v, tb);
+ }
+ Py_XDECREF(result);
+ Py_XDECREF(args);
+ } else {
+ PySys_WriteStderr("sys.excepthook is missing\n");
+ PyErr_Display(exception, v, tb);
+ }
+ Py_XDECREF(exception);
+ Py_XDECREF(v);
+ Py_XDECREF(tb);
+}
+
+void PyErr_Display(PyObject *exception, PyObject *value, PyObject *tb)
+{
+ int err = 0;
+ PyObject *v = value;
+ PyObject *f = PySys_GetObject("stderr");
if (f == NULL)
fprintf(stderr, "lost sys.stderr\n");
else {
if (Py_FlushLine())
PyErr_Clear();
fflush(stdout);
- err = PyTraceBack_Print(tb, f);
+ if (tb && tb != Py_None)
+ err = PyTraceBack_Print(tb, f);
if (err == 0 &&
PyErr_GivenExceptionMatches(exception, PyExc_SyntaxError))
{
@@ -875,8 +907,6 @@
PyFile_WriteString("\n", f);
if (text != NULL)
print_error_text(f, offset, text);
- Py_INCREF(message);
- Py_DECREF(v);
v = message;
/* Can't be bothered to check all those
PyFile_WriteString() calls */
@@ -932,9 +962,6 @@
if (err == 0)
err = PyFile_WriteString("\n", f);
}
- Py_XDECREF(exception);
- Py_XDECREF(v);
- Py_XDECREF(tb);
/* If an error happened here, don't show it.
XXX This is wrong, but too many callers rely on this behavior. */
if (err != 0)
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 3df85ff..9a0a43b 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -107,9 +107,25 @@
}
static char displayhook_doc[] =
-"displayhook(o) -> None\n"
+"displayhook(object) -> None\n"
"\n"
-"Print o to the stdout, and save it in __builtin__._\n";
+"Print an object to sys.stdout and also save it in __builtin__._\n";
+
+static PyObject *
+sys_excepthook(PyObject* self, PyObject* args)
+{
+ PyObject *exc, *value, *tb;
+ if (!PyArg_ParseTuple(args, "OOO:excepthook", &exc, &value, &tb))
+ return NULL;
+ PyErr_Display(exc, value, tb);
+ Py_INCREF(Py_None);
+ return Py_None;
+}
+
+static char excepthook_doc[] =
+"excepthook(exctype, value, traceback) -> None\n"
+"\n"
+"Handle an exception by displaying it with a traceback on sys.stderr.\n";
static PyObject *
sys_exc_info(PyObject *self, PyObject *args)
@@ -378,6 +394,7 @@
/* Might as well keep this in alphabetic order */
{"displayhook", sys_displayhook, 1, displayhook_doc},
{"exc_info", sys_exc_info, 1, exc_info_doc},
+ {"excepthook", sys_excepthook, 1, excepthook_doc},
{"exit", sys_exit, 0, exit_doc},
{"getdefaultencoding", sys_getdefaultencoding, 1,
getdefaultencoding_doc},
@@ -477,13 +494,20 @@
argv -- command line arguments; argv[0] is the script pathname if known\n\
path -- module search path; path[0] is the script directory, else ''\n\
modules -- dictionary of loaded modules\n\
-exitfunc -- you may set this to a function to be called when Python exits\n\
+\n\
+displayhook -- called to show results in an interactive session\n\
+excepthook -- called to handle any uncaught exception other than SystemExit\n\
+ To customize printing in an interactive session or to install a custom\n\
+ top-level exception handler, assign other functions to replace these.\n\
+\n\
+exitfunc -- if sys.exitfunc exists, this routine is called when Python exits\n\
+ Assigning to sys.exitfunc is deprecated; use the atexit module instead.\n\
\n\
stdin -- standard input file object; used by raw_input() and input()\n\
stdout -- standard output file object; used by the print statement\n\
stderr -- standard error object; used for error messages\n\
- By assigning another file object (or an object that behaves like a file)\n\
- to one of these, it is possible to redirect all of the interpreter's I/O.\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_type -- type of last uncaught exception\n\
last_value -- value of last uncaught exception\n\
@@ -498,7 +522,7 @@
because it is thread-safe.\n\
"
#ifndef MS_WIN16
-/* Concatenating string here */
+/* concatenating string here */
"\n\
Static objects:\n\
\n\
@@ -512,15 +536,23 @@
executable -- pathname of this Python interpreter\n\
prefix -- prefix used to find the Python library\n\
exec_prefix -- prefix used to find the machine-specific Python library\n\
-dllhandle -- [Windows only] integer handle of the Python DLL\n\
+"
+#ifdef MS_WINDOWS
+/* concatenating string here */
+"dllhandle -- [Windows only] integer handle of the Python DLL\n\
winver -- [Windows only] version number of the Python DLL\n\
-__stdin__ -- the original stdin; don't use!\n\
-__stdout__ -- the original stdout; don't use!\n\
-__stderr__ -- the original stderr; don't use!\n\
+"
+#endif /* MS_WINDOWS */
+"__stdin__ -- the original stdin; don't touch!\n\
+__stdout__ -- the original stdout; don't touch!\n\
+__stderr__ -- the original stderr; don't touch!\n\
+__displayhook__ -- the original displayhook; don't touch!\n\
+__excepthook__ -- the original excepthook; don't touch!\n\
\n\
Functions:\n\
\n\
displayhook() -- print an object to the screen, and save it in __builtin__._\n\
+excepthook() -- print an exception and its traceback to sys.stderr\n\
exc_info() -- return thread-safe information about the current exception\n\
exit() -- exit the interpreter by raising SystemExit\n\
getrefcount() -- return the reference count for an object (plus one :-)\n\
@@ -530,7 +562,7 @@
setrecursionlimit() -- set the max recursion depth for the interpreter\n\
settrace() -- set the global debug tracing function\n\
"
-#endif
+#endif /* MS_WIN16 */
/* end of sys_doc */ ;
PyObject *
@@ -555,6 +587,10 @@
PyDict_SetItemString(sysdict, "__stdin__", sysin);
PyDict_SetItemString(sysdict, "__stdout__", sysout);
PyDict_SetItemString(sysdict, "__stderr__", syserr);
+ PyDict_SetItemString(sysdict, "__displayhook__",
+ PyDict_GetItemString(sysdict, "displayhook"));
+ PyDict_SetItemString(sysdict, "__excepthook__",
+ PyDict_GetItemString(sysdict, "excepthook"));
Py_XDECREF(sysin);
Py_XDECREF(sysout);
Py_XDECREF(syserr);