[python] [patch] PR python/13329

[python] [patch] PR python/13329

[Phil Muldoon]

This patch changes the behavior of 'python stack-print' to three modes:
full, message or none.  The default has been set to "message".

  full - will print the exception message and the stack.
  message - will print the exception type and message only.
  none - nothing will be printed.

This patch also fixes a bug where we were calling gdbpy_print_stack
after a few PyRun_SimpleString calls.  This is not necessary as that
API deals with the exception internally and prints its own stack.

This is backwards compatible with the deprecated maint set python print-sack.

on - will set the mode to "full".
off - will set the mode to "none".

Tested with no regressions.

Cheers,

Phil

--

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* python/python.c: Declare python_excp_none, python_excp_full,
	python_excp_message, python_excp_enums
	(set_python_excp_mode): New function.
	(_initialize_python): Set 'print-stack' command to an enum
	accepting command.
	(gdbpy_print_stack): Rewrite.
	(eval_python_from_control_command): Do not call gdbpy_print_stack.
	(python_command): Ditto.
        * NEWS: Update 'print-stack' text.

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* gdb.texinfo (Python Commands): Update 'print-stack' to reflect
	the three values it can now take.

2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>

        PR python/13329

	* gdb.python/py-function.exp: Set python print-stack "on" to "full.
	* gdb.python/python.exp: Ditto.
--

diff --git a/gdb/NEWS b/gdb/NEWS
index 1713049..ecf6849 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -23,9 +23,10 @@
      existing one.
 
   ** The "maint set python print-stack on|off" command has been
-     deprecated, and a new command: "set python print-stack on|off" has
-     replaced it.  Additionally, the default for "print-stack" is now
-     "off".
+     deprecated, and a new command: "set python print-stack
+     none|full|message" has replaced it.  Additionally, the default
+     for "print-stack" is now "message", which just prints the error
+     message without the stack trace.
    
   ** A prompt substitution hook (prompt_hook) is now available to the
      Python API.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index d2bdefa..dc5daa9 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21348,11 +21348,12 @@ print-stack}
 
 @kindex set python print-stack
 @item set python print-stack
-By default, @value{GDBN} will not print a stack trace when an error
-occurs in a Python script.  This can be controlled using @code{set
-python print-stack}: if @code{on}, then Python stack printing is
-enabled; if @code{off}, the default, then Python stack printing is
-disabled.
+By default, @value{GDBN} will print only the message component of a
+Python exception when an error occurs in a Python script.  This can be
+controlled using @code{set python print-stack}: if @code{full}, then
+full Python stack printing is enabled; if @code{none}, then Python stack
+and message printing is disabled; if @code{message}, the default, only
+the message component of the error is printed.
 @end table
 
 It is also possible to execute a Python script from the @value{GDBN}
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 108e542..93a80c6 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -35,9 +35,29 @@
 
 #include <ctype.h>
 
-/* True if we should print the stack when catching a Python error,
-   false otherwise.  */
-static int gdbpy_should_print_stack = 0;
+/* Declared constants and enum for python stack printing.  */
+static const char python_excp_none[] = "none";
+static const char python_excp_full[] = "full";
+static const char python_excp_message[] = "message";
+
+/* set python print-stack choices.  */
+static const char *python_excp_enums[] = {
+  python_excp_none,
+  python_excp_full,
+  python_excp_message,
+  NULL
+};
+
+/* 0 if we should not print the stack when catching a Python error,
+   1 to print the full stack, 2 to just print the message.  */
+static int gdbpy_should_print_stack = 2;
+
+/* The extended exception printing variable.  'full' if we want to
+   print the error message and stack, 'none' if we want to print
+   nothing, and 'message' if we only want to print the error
+   message.  */
+static const char *gdbpy_should_print_stack_extended =
+  python_excp_message;
 
 #ifdef HAVE_PYTHON
 
@@ -233,10 +253,7 @@ eval_python_from_control_command (struct command_line *cmd)
   ret = PyRun_SimpleString (script);
   xfree (script);
   if (ret)
-    {
-      gdbpy_print_stack ();
-      error (_("Error while executing Python code."));
-    }
+    error (_("Error while executing Python code."));
 
   do_cleanups (cleanup);
 }
@@ -258,10 +275,7 @@ python_command (char *arg, int from_tty)
   if (arg && *arg)
     {
       if (PyRun_SimpleString (arg))
-	{
-	  gdbpy_print_stack ();
-	  error (_("Error while executing Python code."));
-	}
+	error (_("Error while executing Python code."));
     }
   else
     {
@@ -881,22 +895,57 @@ gdbpy_flush (PyObject *self, PyObject *args, PyObject *kw)
   Py_RETURN_NONE;
 }
 
-/* Print a python exception trace, or print nothing and clear the
-   python exception, depending on gdbpy_should_print_stack.  Only call
-   this if a python exception is set.  */
+/* Print a python exception trace, print just a message, or print
+   nothing and clear the python exception, depending on
+   gdbpy_should_print_stack.  Only call this if a python exception is
+   set.  */
 void
 gdbpy_print_stack (void)
 {
-  if (gdbpy_should_print_stack)
+  switch (gdbpy_should_print_stack)
     {
+      PyObject *ptype, *pvalue, *ptraceback;
+      char *msg = NULL, *type = NULL;
+
+    case 0:
+      /* Print "none", just clear exception.  */
+      PyErr_Clear ();
+      break;
+
+    case 1:
+      /* Print "full" message and backtrace.  */
       PyErr_Print ();
       /* PyErr_Print doesn't necessarily end output with a newline.
 	 This works because Python's stdout/stderr is fed through
 	 printf_filtered.  */
       begin_line ();
+      break;
+
+    case 2:
+      /* Print "message", just error print message.  */
+      PyErr_Fetch (&ptype, &pvalue, &ptraceback);
+
+      /* Fetch the error message contained within ptype, pvalue.  */
+      msg = gdbpy_exception_to_string (ptype, pvalue);
+      type = gdbpy_obj_to_string (ptype);
+      if (msg == NULL)
+	{
+	  /* An error occurred computing the string representation of the
+	     error message.  */
+	  fprintf_filtered (gdb_stderr,
+			    _("Error occurred computing Python error" \
+			      "message.\n"));
+	}
+      else
+	fprintf_filtered (gdb_stderr, "Python Exception %s %s: \n",
+			  type, msg);
+
+      Py_XDECREF (ptype);
+      Py_XDECREF (pvalue);
+      Py_XDECREF (ptraceback);
+      xfree (msg);
+      break;
     }
-  else
-    PyErr_Clear ();
 }
 
 \f
@@ -1106,6 +1155,21 @@ user_show_python (char *args, int from_tty)
   cmd_show_list (user_show_python_list, from_tty, "");
 }
 
+/* When setting the 'python print-stack' with an enum, set the
+   gdbpy_should_print_stack correspondingly.  */
+static void
+set_python_excp_mode (char *args, int i, struct cmd_list_element *c)
+{
+  const char *user_arg = *(const char **) c->var;
+
+  if (strncmp (user_arg, python_excp_none, 4) == 0)
+      gdbpy_should_print_stack = 0;
+  else if (strncmp (user_arg, python_excp_full, 3) == 0)
+      gdbpy_should_print_stack = 1;
+  else if (strncmp (user_arg, python_excp_message, 7) == 0)
+      gdbpy_should_print_stack = 2;
+}
+
 /* Initialize the Python code.  */
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
@@ -1176,14 +1240,16 @@ Enables or disables printing of Python stack traces."),
 		  &user_set_python_list, "set python ", 0,
 		  &setlist);
 
-  add_setshow_boolean_cmd ("print-stack", no_class,
-			   &gdbpy_should_print_stack, _("\
-Enable or disable printing of Python stack dump on error."), _("\
-Show whether Python stack will be printed on error."), _("\
-Enables or disables printing of Python stack traces."),
-			   NULL, NULL,
-			   &user_set_python_list,
-			   &user_show_python_list);
+  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
+			&gdbpy_should_print_stack_extended, _("\
+Set mode for Python stack dump on error."), _("\
+Show the mode of Python stack printing on error."), _("\
+none  == no stack or message will be printed.\n\
+full == a message and a stack will be printed.\n\
+message == an error message without a stack will be printed."),
+			set_python_excp_mode, NULL,
+			&user_set_python_list,
+			&user_show_python_list);
 
 #ifdef HAVE_PYTHON
 #ifdef WITH_PYTHON_PATH
diff --git a/gdb/testsuite/gdb.python/py-function.exp b/gdb/testsuite/gdb.python/py-function.exp
index d579435..f670d52 100644
--- a/gdb/testsuite/gdb.python/py-function.exp
+++ b/gdb/testsuite/gdb.python/py-function.exp
@@ -93,7 +93,7 @@ gdb_py_test_multiple "Test Normal Error" \
   "NormalError ()" "" \
   "end" ""
 
-gdb_test_no_output "set python print-stack on"
+gdb_test_no_output "set python print-stack full"
 gdb_test "print \$normalerror()" "Traceback.*File.*line 5.*in invoke.*RuntimeError.*This is a Normal Error.*" \
     "Test a Runtime error.  There should be a stack trace."
 
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.exp b/gdb/testsuite/gdb.python/py-prettyprint.exp
index b0e7d62..9786d71 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.exp
+++ b/gdb/testsuite/gdb.python/py-prettyprint.exp
@@ -97,7 +97,7 @@ proc run_lang_tests {exefile lang} {
     gdb_test_no_output "python pp_ls_encoding = 'UTF-8'"
     gdb_test "print estring2" "\"embedded \", <incomplete sequence \\\\302>"
 
-    gdb_test_no_output "set python print-stack on"
+    gdb_test_no_output "set python print-stack full"
     gdb_test "print hint_error" "Exception: hint failed\r\nhint_error_val"
 
     gdb_test "print c" " = container \"container\" with 2 elements = {$nl *.0. = 23,$nl *.1. = 72$nl}"
diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index 94d6d0d..2062d00 100644
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -203,12 +203,13 @@ gdb_test "maint set python print-stack off" \
     "Warning: command 'maintenance set python print-stack' is deprecated.*Use 'set python print-stack'.*" \
     "Test deprecation maint set warning."
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is off.*" \
+    "The mode of Python stack printing on error is \"message\".*" \
     "Test print-backtrace show setting. Default off."
-gdb_py_test_silent_cmd "set python print-stack on" \
+gdb_py_test_silent_cmd "set python print-stack full" \
     "Test print-backtrace set setting" 1
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is on.*" \
+    "The mode of Python stack printing on error is \"full\".*" \
+    "Test print-backtrace show setting to full."
 
 # Test prompt substituion
 
@@ -313,7 +314,7 @@ gdb_test_multiple "set extended-prompt \\w " \
 
 gdb_test_multiple "set extended-prompt some param \\p{python print-stack} " \
     "set extended prompt parameter" {
-    -re "\[\r\n\]some param True $" {
+    -re "\[\r\n\]some param full $" {
 	pass "set extended prompt parameter"
     }
 }

Re: [python] [patch] PR python/13329

[Kevin Pouget]

On Wed, Nov 9, 2011 at 4:35 PM, Phil Muldoon <pmuldoon@redhat.com> wrote:
>
> This patch changes the behavior of 'python stack-print' to three modes:
> full, message or none.  The default has been set to "message".
>
>  full - will print the exception message and the stack.
>  message - will print the exception type and message only.
>  none - nothing will be printed.
>
> This patch also fixes a bug where we were calling gdbpy_print_stack
> after a few PyRun_SimpleString calls.  This is not necessary as that
> API deals with the exception internally and prints its own stack.
>
> This is backwards compatible with the deprecated maint set python print-sack.
>
> on - will set the mode to "full".
> off - will set the mode to "none".
>
> Tested with no regressions.
>
> Cheers,
>
> Phil
>

Thanks Phil, that's exactly what I was looking for :)

just a remark,

+         fprintf_filtered (gdb_stderr,
+                           _("Error occurred computing Python error" \
+                             "message.\n"));

this error message sounds strange to me, is it correct?


Cheers,

Kevin

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Kevin Pouget <kevin.pouget@gmail.com> writes:

> Thanks Phil, that's exactly what I was looking for :)
>
> just a remark,
>
> +         fprintf_filtered (gdb_stderr,
> +                           _("Error occurred computing Python error" \
> +                             "message.\n"));
>
> this error message sounds strange to me, is it correct?

Yes, this happens when we cannot get the exception message, but an
exception has been set.  I don't ever expect this error to actually be
seen, but it can happen depending on the state of the interpreter.
Looking at it again, I do see I did miss a space between 'error' and
'message' though!

Cheers,

Phil

Re: [python] [patch] PR python/13329

[Tom Tromey]

>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:

Phil> 2011-11-09  Phil Muldoon  <pmuldoon@redhat.com>
Phil>         PR python/13329

Phil> +/* set python print-stack choices.  */

Capital "s".

Phil> +static const char *python_excp_enums[] = {

I usually put the "{" on a new line here.
It seems more GNU-ish to me.

Phil> +/* 0 if we should not print the stack when catching a Python error,
Phil> +   1 to print the full stack, 2 to just print the message.  */
Phil> +static int gdbpy_should_print_stack = 2;

It is more normal, though not exclusively the case (I think), to just
use the string constants here.  Because they are constant strings you
can just compare them with ==.

That is, you can just remove this variable.

Phil> +/* The extended exception printing variable.  'full' if we want to
Phil> +   print the error message and stack, 'none' if we want to print
Phil> +   nothing, and 'message' if we only want to print the error
Phil> +   message.  */
Phil> +static const char *gdbpy_should_print_stack_extended =
Phil> +  python_excp_message;

... and rename this to gdbpy_should_print_stack and use it directly.

Phil> +/* When setting the 'python print-stack' with an enum, set the
Phil> +   gdbpy_should_print_stack correspondingly.  */
Phil> +static void
Phil> +set_python_excp_mode (char *args, int i, struct cmd_list_element *c)

With the above change you won't need this function.

Phil> +  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
Phil> +			&gdbpy_should_print_stack_extended, _("\
Phil> +Set mode for Python stack dump on error."), _("\
Phil> +Show the mode of Python stack printing on error."), _("\
Phil> +none  == no stack or message will be printed.\n\
Phil> +full == a message and a stack will be printed.\n\
Phil> +message == an error message without a stack will be printed."),
Phil> +			set_python_excp_mode, NULL,
Phil> +			&user_set_python_list,
Phil> +			&user_show_python_list);

I'm surprised this is backward compatible.

Phil> -gdb_test_no_output "set python print-stack on"
Phil> +gdb_test_no_output "set python print-stack full"

You should leave in some compatibility tests for the old values.

I didn't look but you should try the old code to see exactly what values
it accepted.  I thought the boolean set/shows took more than just on/off.

Tom

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Tom Tromey <tromey@redhat.com> writes:

> Phil> +/* 0 if we should not print the stack when catching a Python error,
> Phil> +   1 to print the full stack, 2 to just print the message.  */
> Phil> +static int gdbpy_should_print_stack = 2;
>
> It is more normal, though not exclusively the case (I think), to just
> use the string constants here.  Because they are constant strings you
> can just compare them with ==.
>
> That is, you can just remove this variable.
>
> Phil> +/* The extended exception printing variable.  'full' if we want to
> Phil> +   print the error message and stack, 'none' if we want to print
> Phil> +   nothing, and 'message' if we only want to print the error
> Phil> +   message.  */
> Phil> +static const char *gdbpy_should_print_stack_extended =
> Phil> +  python_excp_message;
>
> ... and rename this to gdbpy_should_print_stack and use it directly.
>
> Phil> +/* When setting the 'python print-stack' with an enum, set the
> Phil> +   gdbpy_should_print_stack correspondingly.  */
> Phil> +static void
> Phil> +set_python_excp_mode (char *args, int i, struct cmd_list_element *c)

I have to keep/add these functions around to be compatible with "maint
set python print-stack" which is a boolean parameter.  So it was my view
we still operate on the gdbpy_should_print_stack variable in
gdbpy_print_stack function, and have the "set function" just set
gdbpy_should_print_stack from the enum command.  I can do what you wish,
but I would have to write a "set" function to set the enum constant
instead.

> With the above change you won't need this function.
>
> Phil> +  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
> Phil> +			&gdbpy_should_print_stack_extended, _("\
> Phil> +Set mode for Python stack dump on error."), _("\
> Phil> +Show the mode of Python stack printing on error."), _("\
> Phil> +none  == no stack or message will be printed.\n\
> Phil> +full == a message and a stack will be printed.\n\
> Phil> +message == an error message without a stack will be printed."),
> Phil> +			set_python_excp_mode, NULL,
> Phil> +			&user_set_python_list,
> Phil> +			&user_show_python_list);
>
> I'm surprised this is backward compatible.

The user command "set python print-stack" has not been published in a
release so it is not compatible; I believe it is within our API pledge
to change whatever we like until that feature is released.  "maint set
python print-stack" still works, but is deprecated. For the variable
gdbpy_should_print_stack, 0 is still off, 1 is full, 2 is message only.
The "maint set python print-stack" will only ever set off or full.

> Phil> -gdb_test_no_output "set python print-stack on"
> Phil> +gdb_test_no_output "set python print-stack full"
>
> You should leave in some compatibility tests for the old values.

Do you mean use "maint set python print-stack" here?

> I didn't look but you should try the old code to see exactly what values
> it accepted.  I thought the boolean set/shows took more than just on/off.

I will, but the result remains the same. 0 for off, > 0 for on.

Cheers

Phil

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Phil Muldoon <pmuldoon@redhat.com> writes:

Ping.  I want to target this for 7.4.

Cheers,

Phil
> Tom Tromey <tromey@redhat.com> writes:
>
>> Phil> +/* 0 if we should not print the stack when catching a Python error,
>> Phil> +   1 to print the full stack, 2 to just print the message.  */
>> Phil> +static int gdbpy_should_print_stack = 2;
>>
>> It is more normal, though not exclusively the case (I think), to just
>> use the string constants here.  Because they are constant strings you
>> can just compare them with ==.
>>
>> That is, you can just remove this variable.
>>
>> Phil> +/* The extended exception printing variable.  'full' if we want to
>> Phil> +   print the error message and stack, 'none' if we want to print
>> Phil> +   nothing, and 'message' if we only want to print the error
>> Phil> +   message.  */
>> Phil> +static const char *gdbpy_should_print_stack_extended =
>> Phil> +  python_excp_message;
>>
>> ... and rename this to gdbpy_should_print_stack and use it directly.
>>
>> Phil> +/* When setting the 'python print-stack' with an enum, set the
>> Phil> +   gdbpy_should_print_stack correspondingly.  */
>> Phil> +static void
>> Phil> +set_python_excp_mode (char *args, int i, struct cmd_list_element *c)
>
> I have to keep/add these functions around to be compatible with "maint
> set python print-stack" which is a boolean parameter.  So it was my view
> we still operate on the gdbpy_should_print_stack variable in
> gdbpy_print_stack function, and have the "set function" just set
> gdbpy_should_print_stack from the enum command.  I can do what you wish,
> but I would have to write a "set" function to set the enum constant
> instead.
>
>> With the above change you won't need this function.
>>
>> Phil> +  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
>> Phil> +			&gdbpy_should_print_stack_extended, _("\
>> Phil> +Set mode for Python stack dump on error."), _("\
>> Phil> +Show the mode of Python stack printing on error."), _("\
>> Phil> +none  == no stack or message will be printed.\n\
>> Phil> +full == a message and a stack will be printed.\n\
>> Phil> +message == an error message without a stack will be printed."),
>> Phil> +			set_python_excp_mode, NULL,
>> Phil> +			&user_set_python_list,
>> Phil> +			&user_show_python_list);
>>
>> I'm surprised this is backward compatible.
>
> The user command "set python print-stack" has not been published in a
> release so it is not compatible; I believe it is within our API pledge
> to change whatever we like until that feature is released.  "maint set
> python print-stack" still works, but is deprecated. For the variable
> gdbpy_should_print_stack, 0 is still off, 1 is full, 2 is message only.
> The "maint set python print-stack" will only ever set off or full.
>
>> Phil> -gdb_test_no_output "set python print-stack on"
>> Phil> +gdb_test_no_output "set python print-stack full"
>>
>> You should leave in some compatibility tests for the old values.
>
> Do you mean use "maint set python print-stack" here?
>
>> I didn't look but you should try the old code to see exactly what values
>> it accepted.  I thought the boolean set/shows took more than just on/off.
>
> I will, but the result remains the same. 0 for off, > 0 for on.
>
> Cheers
>
> Phil

Re: [python] [patch] PR python/13329

[Tom Tromey]

>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:

Phil> The user command "set python print-stack" has not been published in a
Phil> release so it is not compatible

Ok, I see.  I didn't remember that.

I think you should just change the 'maint' one to follow.
If you want you can add a compatibility mode, but it is up to you.
I don't think we should promise any kind of compatibility around "maint"
commands.

Tom> You should leave in some compatibility tests for the old values.

Phil> Do you mean use "maint set python print-stack" here?

I did, but don't bother with that now.

Tom

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Tom Tromey <tromey@redhat.com> writes:

>>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:
>
> Phil> The user command "set python print-stack" has not been published in a
> Phil> release so it is not compatible
>
> Ok, I see.  I didn't remember that.
>
> I think you should just change the 'maint' one to follow.
> If you want you can add a compatibility mode, but it is up to you.
> I don't think we should promise any kind of compatibility around "maint"
> commands.
>
> Tom> You should leave in some compatibility tests for the old values.
>
> Phil> Do you mean use "maint set python print-stack" here?
>
> I did, but don't bother with that now.

I updated the patch.  This patch removes the "maint" command entirely.

Needs a doc/code review.

OK?

Cheers,

Phil

--

2011-12-15  Phil Muldoon  <pmuldoon@redhat.com>

	* testsuite/gdb.python/py-function.exp: Change "on" to "full" for
	python print-stack.  Add set/show python print-stack
	off|full|message tests.

2011-12-15  Phil Muldoon  <pmuldoon@redhat.com>

	* python/python.c: Define python_excp_enums.
	(eval_python_from_control_command): Do not call gdbpy_print_stack.
	(python_command): Ditto.
	(gdbpy_print_stack): Rewrite to use new enum constants.
	(maint_set_python): Remove function.
	(maint_show_python): Ditto.
	(_initialize_python): Do not add "maint" commands.  Add "set/show
	python print-stack commands".
	* NEWS: Update to reflect removal for "maint set/show
	print-stack"

2011-12-15  Phil Muldoon  <pmuldoon@redhat.com>

	* doc/gdb.texinfo (Python Commands): Remove "maint set/show print
	stack".  Add documentation for "set/show python print-stack".
--

diff --git a/gdb/NEWS b/gdb/NEWS
index 02f73a5..43345a9 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -31,9 +31,10 @@
      existing one.
 
   ** The "maint set python print-stack on|off" command has been
-     deprecated, and a new command: "set python print-stack on|off" has
-     replaced it.  Additionally, the default for "print-stack" is now
-     "off".
+     removed.  A new command: "set python print-stack
+     none|full|message" has replaced it.  Additionally, the default
+     for "print-stack" is now "message", which just prints the error
+     message without the stack trace.
    
   ** A prompt substitution hook (prompt_hook) is now available to the
      Python API.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 925e66a..4787b82 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21447,18 +21447,14 @@ End with a line saying just "end".
 23
 @end smallexample
 
-@kindex maint set python print-stack
-@item maint set python print-stack
-This command is now deprecated.  Instead use @code{set python
-print-stack} 
-
 @kindex set python print-stack
 @item set python print-stack
-By default, @value{GDBN} will not print a stack trace when an error
-occurs in a Python script.  This can be controlled using @code{set
-python print-stack}: if @code{on}, then Python stack printing is
-enabled; if @code{off}, the default, then Python stack printing is
-disabled.
+By default, @value{GDBN} will print only the message component of a
+Python exception when an error occurs in a Python script.  This can be
+controlled using @code{set python print-stack}: if @code{full}, then
+full Python stack printing is enabled; if @code{none}, then Python stack
+and message printing is disabled; if @code{message}, the default, only
+the message component of the error is printed.
 @end table
 
 It is also possible to execute a Python script from the @value{GDBN}
diff --git a/gdb/python/python.c b/gdb/python/python.c
index b0b9a9c..9b00cdc 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -35,9 +35,25 @@
 
 #include <ctype.h>
 
-/* True if we should print the stack when catching a Python error,
-   false otherwise.  */
-static int gdbpy_should_print_stack = 0;
+/* Declared constants and enum for python stack printing.  */
+static const char python_excp_none[] = "none";
+static const char python_excp_full[] = "full";
+static const char python_excp_message[] = "message";
+
+/* "set python print-stack" choices.  */
+static const char *python_excp_enums[] =
+  {
+    python_excp_none,
+    python_excp_full,
+    python_excp_message,
+    NULL
+  };
+
+/* The exception printing variable.  'full' if we want to print the
+   error message and stack, 'none' if we want to print nothing, and
+   'message' if we only want to print the error message.  'message' is
+   the default.  */
+static const char *gdbpy_should_print_stack = python_excp_message;
 
 #ifdef HAVE_PYTHON
 
@@ -233,10 +249,7 @@ eval_python_from_control_command (struct command_line *cmd)
   ret = PyRun_SimpleString (script);
   xfree (script);
   if (ret)
-    {
-      gdbpy_print_stack ();
-      error (_("Error while executing Python code."));
-    }
+    error (_("Error while executing Python code."));
 
   do_cleanups (cleanup);
 }
@@ -258,10 +271,7 @@ python_command (char *arg, int from_tty)
   if (arg && *arg)
     {
       if (PyRun_SimpleString (arg))
-	{
-	  gdbpy_print_stack ();
-	  error (_("Error while executing Python code."));
-	}
+	error (_("Error while executing Python code."));
     }
   else
     {
@@ -881,13 +891,20 @@ gdbpy_flush (PyObject *self, PyObject *args, PyObject *kw)
   Py_RETURN_NONE;
 }
 
-/* Print a python exception trace, or print nothing and clear the
-   python exception, depending on gdbpy_should_print_stack.  Only call
-   this if a python exception is set.  */
+/* Print a python exception trace, print just a message, or print
+   nothing and clear the python exception, depending on
+   gdbpy_should_print_stack.  Only call this if a python exception is
+   set.  */
 void
 gdbpy_print_stack (void)
 {
-  if (gdbpy_should_print_stack)
+  /* Print "none", just clear exception.  */
+  if (gdbpy_should_print_stack == python_excp_none)
+    {
+      PyErr_Clear ();
+    }
+  /* Print "full" message and backtrace.  */
+  else if (gdbpy_should_print_stack == python_excp_full)
     {
       PyErr_Print ();
       /* PyErr_Print doesn't necessarily end output with a newline.
@@ -895,8 +912,34 @@ gdbpy_print_stack (void)
 	 printf_filtered.  */
       begin_line ();
     }
+  /* Print "message", just error print message.  */
   else
-    PyErr_Clear ();
+    {
+      PyObject *ptype, *pvalue, *ptraceback;
+      char *msg = NULL, *type = NULL;
+
+      PyErr_Fetch (&ptype, &pvalue, &ptraceback);
+
+      /* Fetch the error message contained within ptype, pvalue.  */
+      msg = gdbpy_exception_to_string (ptype, pvalue);
+      type = gdbpy_obj_to_string (ptype);
+      if (msg == NULL)
+	{
+	  /* An error occurred computing the string representation of the
+	     error message.  */
+	  fprintf_filtered (gdb_stderr,
+			    _("Error occurred computing Python error"	\
+			      "message.\n"));
+	}
+      else
+	fprintf_filtered (gdb_stderr, "Python Exception %s %s: \n",
+			  type, msg);
+
+      Py_XDECREF (ptype);
+      Py_XDECREF (pvalue);
+      Py_XDECREF (ptraceback);
+      xfree (msg);
+    }
 }
 
 \f
@@ -1062,33 +1105,11 @@ gdbpy_breakpoint_has_py_cond (struct breakpoint_object *bp_obj)
 
 \f
 
-/* Lists for 'maint set python' commands.  */
-
-static struct cmd_list_element *maint_set_python_list;
-static struct cmd_list_element *maint_show_python_list;
-
 /* Lists for 'set python' commands.  */
 
 static struct cmd_list_element *user_set_python_list;
 static struct cmd_list_element *user_show_python_list;
 
-/* Function for use by 'maint set python' prefix command.  */
-
-static void
-maint_set_python (char *args, int from_tty)
-{
-  help_list (maint_set_python_list, "maintenance set python ",
-	     class_deprecated, gdb_stdout);
-}
-
-/* Function for use by 'maint show python' prefix command.  */
-
-static void
-maint_show_python (char *args, int from_tty)
-{
-  cmd_show_list (maint_show_python_list, from_tty, "");
-}
-
 /* Function for use by 'set python' prefix command.  */
 
 static void
@@ -1138,33 +1159,6 @@ This command is only a placeholder.")
 #endif /* HAVE_PYTHON */
 	   );
 
-  add_prefix_cmd ("python", no_class, maint_show_python,
-		  _("Prefix command for python maintenance settings."),
-		  &maint_show_python_list, "maintenance show python ", 0,
-		  &maintenance_show_cmdlist);
-  add_prefix_cmd ("python", no_class, maint_set_python,
-		  _("Prefix command for python maintenance settings."),
-		  &maint_set_python_list, "maintenance set python ", 0,
-		  &maintenance_set_cmdlist);
-
-  add_setshow_boolean_cmd ("print-stack", class_maintenance,
-			   &gdbpy_should_print_stack, _("\
-Enable or disable printing of Python stack dump on error."), _("\
-Show whether Python stack will be printed on error."), _("\
-Enables or disables printing of Python stack traces."),
-			   NULL, NULL,
-			   &maint_set_python_list,
-			   &maint_show_python_list);
-
-  /* Deprecate maint set/show python print-stack in favour of
-     non-maintenance alternatives.  */
-  cmd_name = "print-stack";
-  cmd = lookup_cmd (&cmd_name, maint_set_python_list, "", -1, 0);
-  deprecate_cmd (cmd, "set python print-stack");
-  cmd_name = "print-stack"; /* Reset name.  */
-  cmd = lookup_cmd (&cmd_name, maint_show_python_list, "", -1, 0);
-  deprecate_cmd (cmd, "show python print-stack");
-
   /* Add set/show python print-stack.  */
   add_prefix_cmd ("python", no_class, user_show_python,
 		  _("Prefix command for python preference settings."),
@@ -1176,14 +1170,16 @@ Enables or disables printing of Python stack traces."),
 		  &user_set_python_list, "set python ", 0,
 		  &setlist);
 
-  add_setshow_boolean_cmd ("print-stack", no_class,
-			   &gdbpy_should_print_stack, _("\
-Enable or disable printing of Python stack dump on error."), _("\
-Show whether Python stack will be printed on error."), _("\
-Enables or disables printing of Python stack traces."),
-			   NULL, NULL,
-			   &user_set_python_list,
-			   &user_show_python_list);
+  add_setshow_enum_cmd ("print-stack", no_class, python_excp_enums,
+			&gdbpy_should_print_stack, _("\
+Set mode for Python stack dump on error."), _("\
+Show the mode of Python stack printing on error."), _("\
+none  == no stack or message will be printed.\n\
+full == a message and a stack will be printed.\n\
+message == an error message without a stack will be printed."),
+			NULL, NULL,
+			&user_set_python_list,
+			&user_show_python_list);
 
 #ifdef HAVE_PYTHON
 #ifdef WITH_PYTHON_PATH
diff --git a/gdb/testsuite/gdb.python/py-function.exp b/gdb/testsuite/gdb.python/py-function.exp
index d579435..f670d52 100644
--- a/gdb/testsuite/gdb.python/py-function.exp
+++ b/gdb/testsuite/gdb.python/py-function.exp
@@ -93,7 +93,7 @@ gdb_py_test_multiple "Test Normal Error" \
   "NormalError ()" "" \
   "end" ""
 
-gdb_test_no_output "set python print-stack on"
+gdb_test_no_output "set python print-stack full"
 gdb_test "print \$normalerror()" "Traceback.*File.*line 5.*in invoke.*RuntimeError.*This is a Normal Error.*" \
     "Test a Runtime error.  There should be a stack trace."
 
diff --git a/gdb/testsuite/gdb.python/py-prettyprint.exp b/gdb/testsuite/gdb.python/py-prettyprint.exp
index b0e7d62..9786d71 100644
--- a/gdb/testsuite/gdb.python/py-prettyprint.exp
+++ b/gdb/testsuite/gdb.python/py-prettyprint.exp
@@ -97,7 +97,7 @@ proc run_lang_tests {exefile lang} {
     gdb_test_no_output "python pp_ls_encoding = 'UTF-8'"
     gdb_test "print estring2" "\"embedded \", <incomplete sequence \\\\302>"
 
-    gdb_test_no_output "set python print-stack on"
+    gdb_test_no_output "set python print-stack full"
     gdb_test "print hint_error" "Exception: hint failed\r\nhint_error_val"
 
     gdb_test "print c" " = container \"container\" with 2 elements = {$nl *.0. = 23,$nl *.1. = 72$nl}"
diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index 94d6d0d..290a083 100644
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -195,20 +195,15 @@ gdb_test "python gdb.write(\"Error stream\\n\", stream=gdb.STDERR)" "Error strea
 gdb_test "python gdb.write(\"Normal stream\\n\", stream=gdb.STDOUT)" "Normal stream" "Test stdout write"
 gdb_test "python gdb.write(\"Log stream\\n\", stream=gdb.STDLOG)" "Log stream" "Test stdlog write"
 
-# Deprecate maint set/show python print-stack
-gdb_test "maint show python print-stack" \
-    "Warning: command 'maintenance show python print-stack' is deprecated.*Use 'show python print-stack'.*" \
-    "Test deprecation maint show warning."
-gdb_test "maint set python print-stack off" \
-    "Warning: command 'maintenance set python print-stack' is deprecated.*Use 'set python print-stack'.*" \
-    "Test deprecation maint set warning."
+# print-stack
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is off.*" \
-    "Test print-backtrace show setting. Default off."
-gdb_py_test_silent_cmd "set python print-stack on" \
+    "The mode of Python stack printing on error is \"message\".*" \
+    "Test print-backtrace show setting. Default is message."
+gdb_py_test_silent_cmd "set python print-stack full" \
     "Test print-backtrace set setting" 1
 gdb_test "show python print-stack" \
-    "Whether Python stack will be printed on error is on.*" \
+    "The mode of Python stack printing on error is \"full\".*" \
+    "Test print-backtrace show setting to full."
 
 # Test prompt substituion
 
@@ -313,7 +308,63 @@ gdb_test_multiple "set extended-prompt \\w " \
 
 gdb_test_multiple "set extended-prompt some param \\p{python print-stack} " \
     "set extended prompt parameter" {
-    -re "\[\r\n\]some param True $" {
+    -re "\[\r\n\]some param full $" {
 	pass "set extended prompt parameter"
     }
 }
+
+# Start with a fresh gdb.
+clean_restart ${testfile}
+
+# The following tests require execution.
+
+if ![runto_main] then {
+    fail "Can't run to main"
+    return 0
+}
+
+# print-stack settings
+gdb_test "show python print-stack" \
+    "The mode of Python stack printing on error is \"message\".*" \
+    "Test print-backtrace show setting. Default is message."
+gdb_py_test_silent_cmd "set python print-stack full" \
+    "Test print-backtrace set setting" 1
+gdb_test "show python print-stack" \
+    "The mode of Python stack printing on error is \"full\".*" \
+    "Test print-backtrace show setting to full."
+gdb_py_test_silent_cmd "set python print-stack none" \
+    "Test print-backtrace set setting" 1
+gdb_test "show python print-stack" \
+    "The mode of Python stack printing on error is \"none\".*" \
+    "Test print-backtrace show setting to none."
+
+gdb_py_test_silent_cmd "set python print-stack message" \
+    "Test print-backtrace set setting" 1
+
+gdb_py_test_multiple "prompt substitution readline" \
+  "python" "" \
+  "pCounter = 0" "" \
+  "def error_prompt(current):" "" \
+  "   raise RuntimeError(\"Python exception called\")" "" \
+  "end" ""
+
+gdb_test_multiple "python gdb.prompt_hook = error_prompt" "set the hook" {
+    -re "Python Exception <type 'exceptions.RuntimeError'> Python exception called.*" {
+	pass "set hook"
+    }
+}
+
+gdb_py_test_silent_cmd "python gdb.prompt_hook = None" \
+    "set the hook to default" 1
+
+gdb_py_test_silent_cmd "set python print-stack full" \
+    "Test print-backtrace set setting" 1
+
+gdb_test_multiple "python gdb.prompt_hook = error_prompt" "set the hook" {
+    -re "Traceback.*File.*line.*RuntimeError.*Python exception called.*" {
+	pass "set hook"
+    }
+}
+
+gdb_py_test_silent_cmd "python gdb.prompt_hook = None" \
+    "set the hook to default" 1

Re: [python] [patch] PR python/13329

[Eli Zaretskii]

> From: Phil Muldoon <pmuldoon@redhat.com>
> Cc: gdb-patches@sourceware.org, eli@gnu.org
> Date: Thu, 15 Dec 2011 17:42:44 +0000
> 
> I updated the patch.  This patch removes the "maint" command entirely.
> 
> Needs a doc/code review.

The documentation part is okay.

Thanks.

Re: [python] [patch] PR python/13329

[Tom Tromey]

>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:

Phil> I updated the patch.  This patch removes the "maint" command entirely.
Phil> Needs a doc/code review.

Phil> OK?

Ok.  Thanks.

Tom

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Tom Tromey <tromey@redhat.com> writes:

>>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:
>
> Phil> I updated the patch.  This patch removes the "maint" command entirely.
> Phil> Needs a doc/code review.
>
> Phil> OK?
>
> Ok.  Thanks.

In the current 7.4 release tarball we have set python print-stack
on|off.  Beyond that pre-release, it has never been released before.  As
7.4 is unreleased as yet, we can change it to this new functionality.
Ok for 7.4 branch too (to avoid API breakage)?

Cheers,

Phil

Re: [python] [patch] PR python/13329

[Tom Tromey]

Phil> In the current 7.4 release tarball we have set python print-stack
Phil> on|off.  Beyond that pre-release, it has never been released before.  As
Phil> 7.4 is unreleased as yet, we can change it to this new functionality.
Phil> Ok for 7.4 branch too (to avoid API breakage)?

Yes please.  Thanks.

Tom

Re: [python] [patch] PR python/13329

[Phil Muldoon]

Tom Tromey <tromey@redhat.com> writes:

> Phil> In the current 7.4 release tarball we have set python print-stack
> Phil> on|off.  Beyond that pre-release, it has never been released before.  As
> Phil> 7.4 is unreleased as yet, we can change it to this new functionality.
> Phil> Ok for 7.4 branch too (to avoid API breakage)?
>
> Yes please.  Thanks.

So committed, to head and branch.  Also, an additional fix, an obvious
fix to HEAD where there were path typos in ChangeLog doc/ChangeLog

Cheers,

Phil