Extension Language API

* configure.ac (libpython checking): Remove all but python.o from
	CONFIG_OBS.  Remove all but python.c from CONFIG_SRCS.
	* configure: Regenerate.

	* Makefile.in (SFILES): Add extension.c.
	(HFILES_NO_SRCDIR): Add extension.h, extension-priv.h
	(COMMON_OBS): Add extension.o.
	* extension.h: New file.
	* extension-priv.h: New file.
	* extension.c: New file.

	* python/python-internal.h: #include "extension.h".
	(gdbpy_auto_load_enabled): Declare.
	(gdbpy_apply_val_pretty_printer): Declare.
	(gdbpy_apply_frame_filter): Declare.
	(gdbpy_preserve_values): Declare.
	(gdbpy_breakpoint_cond_says_stop): Declare.
	(gdbpy_breakpoint_has_cond): Declare.
	(void source_python_script_for_objfile): Delete.
	* python/python.c: #include "extension-priv.h".
	Delete inclusion of "observer.h".
	(extension_language_python): Moved here and renamed from
	script_language_python in py-auto-load.c.
	Redefined to be of type extension_language_defn.
	(python_extension_script_ops): New global.
	(python_extension_ops): New global.
	(struct python_env): New member previous_active.
	(restore_python_env): Call restore_active_ext_lang.
	(ensure_python_env): Call set_active_ext_lang.
	(gdbpy_clear_quit_flag): Renamed from clear_quit_flag, made static.
	New arg extlang.
	(gdbpy_set_quit_flag): Renamed from set_quit_flag, made static.
	New arg extlang.
	(gdbpy_check_quit_flag): Renamed from check_quit_flag, made static.
	New arg extlang.
	(gdbpy_eval_from_control_command): Renamed from
	eval_python_from_control_command, made static.  New arg extlang.
	(gdbpy_source_script) Renamed from source_python_script, made static.
	New arg extlang.
	(gdbpy_before_prompt_hook): Renamed from before_prompt_hook.  Change
	result to int.  New arg extlang.
	(gdbpy_source_objfile_script): Renamed from
	source_python_script_for_objfile, made static.  New arg extlang.
	(gdbpy_start_type_printers): Renamed from start_type_printers, made
	static.  New args extlang, extlang_printers.  Change result type to
	"void".
	(gdbpy_apply_type_printers): Renamed from apply_type_printers, made
	static.  New arg extlang.  Rename arg printers to extlang_printers
	and change type to ext_lang_type_printers *.
	(gdbpy_free_type_printers): Renamed from free_type_printers, made
	static.  Replace argument arg with extlang, extlang_printers.
	(!HAVE_PYTHON, eval_python_from_control_command): Delete.
	(!HAVE_PYTHON, source_python_script): Delete.
	(!HAVE_PYTHON, gdbpy_should_stop): Delete.
	(!HAVE_PYTHON, gdbpy_breakpoint_has_py_cond): Delete.
	(!HAVE_PYTHON, start_type_printers): Delete.
	(!HAVE_PYTHON, apply_type_printers): Delete.
	(!HAVE_PYTHON, free_type_printers): Delete.
	(_initialize_python): Delete call to observer_attach_before_prompt.
	(finalize_python): Set/restore active extension language.
	(gdbpy_finish_initialization) Renamed from
	finish_python_initialization, made static.  New arg extlang.
	(gdbpy_initialized): New function.
	* python/python.h: #include "extension.h".  Delete #include
	"value.h", "mi/mi-cmds.h".
	(extension_language_python): Declare.
	(GDBPY_AUTO_FILE_NAME): Delete.
	(enum py_bt_status): Moved to extension.h and renamed to
	ext_lang_bt_status.
	(enum frame_filter_flags): Moved to extension.h.
	(enum py_frame_args): Moved to extension.h and renamed to
	ext_lang_frame_args.
	(finish_python_initialization): Delete.
	(eval_python_from_control_command): Delete.
	(source_python_script): Delete.
	(apply_val_pretty_printer): Delete.
	(apply_frame_filter): Delete.
	(preserve_python_values): Delete.
	(gdbpy_script_language_defn): Delete.
	(gdbpy_should_stop, gdbpy_breakpoint_has_py_cond): Delete.
	(start_type_printers, apply_type_printers, free_type_printers): Delete.

	* auto-load.c: #include "extension.h".
	(GDB_AUTO_FILE_NAME): Delete.
	(auto_load_gdb_scripts_enabled): Make public.  New arg extlang.
	(script_language_gdb): Delete, moved to extension.c and renamed to
	extension_language_gdb.
	(source_gdb_script_for_objfile): Delete.
	(auto_load_pspace_info): New member unsupported_script_warning_printed.
	(loaded_script): Change type of language member to
	struct extension_language_defn *.
	(init_loaded_scripts_info): Initialize
	unsupported_script_warning_printed.
	(maybe_add_script): Make static.  Change type of language arg to
	struct extension_language_defn *.
	(clear_section_scripts): Reset unsupported_script_warning_printed.
	(auto_load_objfile_script_1): Rewrite to use extension language API.
	(auto_load_objfile_script): Make public.  Remove support-compiled-in
	and auto-load-enabled checks, moved to auto_load_scripts_for_objfile.
	(source_section_scripts): Rewrite to use extension language API.
	(load_auto_scripts_for_objfile): Rewrite to use
	auto_load_scripts_for_objfile.
	(collect_matching_scripts_data): Change type of language member to
	struct extension_language_defn *.
	(auto_load_info_scripts): Change type of language arg to
	struct extension_language_defn *.
	(unsupported_script_warning_print): New function.
	(script_not_found_warning_print): Make static.
	(_initialize_auto_load): Rewrite construction of scripts-directory
	help.
	* auto-load.h (struct objfile): Add forward decl.
	(struct script_language): Delete.
	(struct auto_load_pspace_info): Add forward decl.
	(struct extension_language_defn): Add forward decl.
	(maybe_add_script): Delete.
	(auto_load_objfile_script): Declare.
	(script_not_found_warning_print): Delete.
	(auto_load_info_scripts): Update prototype.
	(auto_load_gdb_scripts_enabled): Declare.
	* python/py-auto-load.c (gdbpy_auto_load_enabled): Renamed from
	auto_load_python_scripts_enabled and made public.
	(script_language_python): Delete, moved to python.c.
	(gdbpy_script_language_defn): Delete.
	(info_auto_load_python_scripts): Update to use
	extension_language_python.

	* breakpoint.c (condition_command): Replace call to
	gdbpy_breakpoint_has_py_cond with call to get_breakpoint_cond_ext_lang.
	(bpstat_check_breakpoint_conditions): Replace call to gdbpy_should_stop
	with call to breakpoint_ext_lang_cond_says_stop.
	* python/py-breakpoint.c (gdbpy_breakpoint_cond_says_stop): Renamed
	from gdbpy_should_stop.  Change result type to enum scr_bp_stop.
	New arg slang.  Return SCR_BP_STOP_UNSET if py_bp_object is NULL.
	(gdbpy_breakpoint_has_cond): Renamed from gdbpy_breakpoint_has_py_cond.
	New arg slang.
	(local_setattro): Print name of extension language with existing
	stop condition.

	* valprint.c (val_print, value_print): Update to call
	apply_ext_lang_val_pretty_printer.
	* cp-valprint.c (cp_print_value): Update call to
	apply_ext_lang_val_pretty_printer.
	* python/py-prettyprint.c: Remove #ifdef HAVE_PYTHON.
	(gdbpy_apply_val_pretty_printer): Renamed from
	apply_val_pretty_printer.  New arg extlang.
	(!HAVE_PYTHON, apply_val_pretty_printer): Delete.

	* cli/cli-cmds.c (source_script_from_stream): Rewrite to use
	extension language API.
	* cli/cli-script.c (execute_control_command): Update to call
	eval_ext_lang_from_control_command.

	* mi/mi-cmd-stack.c (mi_cmd_stack_list_frames): Update to use
	enum ext_lang_bt_status values.  Update call to
	apply_ext_lang_frame_filter.
	(mi_cmd_stack_list_locals): Ditto.
	(mi_cmd_stack_list_args): Ditto.
	(mi_cmd_stack_list_variables): Ditto.
	* mi/mi-main.c: Delete #include "python/python-internal.h".
	Add #include "extension.h".
	(mi_cmd_list_features): Replace reference to python internal variable
	gdb_python_initialized with call to ext_lang_initialized_p.

	* stack.c (backtrace_command_1): Update to use enum ext_lang_bt_status.
	Update to use enum ext_lang_frame_args.  Update to call
	apply_ext_lang_frame_filter.
	* python/py-framefilter.c (extract_sym): Update to use enum
	ext_lang_bt_status.
	(extract_value, py_print_type, py_print_value): Ditto.
	(py_print_single_arg, enumerate_args, enumerate_locals): Ditto.
	(py_mi_print_variables, py_print_locals, py_print_args): Ditto.
	(py_print_frame): Ditto.
	(gdbpy_apply_frame_filter): Renamed from apply_frame_filter.
	New arg extlang.  Update to use enum ext_lang_bt_status.

	* top.c (gdb_init): Delete #ifdef HAVE_PYTHON call to
	finish_python_initialization.  Replace with call to
	finish_ext_lang_initialization.

	* typeprint.c (do_free_global_table): Update to call
	free_ext_lang_type_printers.
	(create_global_typedef_table): Update to call
	start_ext_lang_type_printers.
	(find_global_typedef): Update to call apply_ext_lang_type_printers.
	* typeprint.h (struct ext_lang_type_printers): Add forward decl.
	(type_print_options): Change type of global_printers from "void *"
	to "struct ext_lang_type_printers *".

	* value.c (preserve_values): Update to call preserve_ext_lang_values.
	* python/py-value.c: Remove #ifdef HAVE_PYTHON.
	(gdbpy_preserve_values): Renamed from preserve_python_values.
	New arg extlang.
	(!HAVE_PYTHON, preserve_python_values): Delete.

	* utils.c (quit_flag): Delete, moved to extension.c.
	(clear_quit_flag, set_quit_flag, check_quit_flag): Delete, moved to
	extension.c.

	* eval.c: Delete #include "python/python.h".
	* main.c: Delete #include "python/python.h".

	* defs.h: Update comment.

	testsuite/

	* gdb.python/py-breakpoint.exp (test_bkpt_eval_funcs): Update expected
	output.

	* gdb.gdb/python-interrupts.exp: New file.

gdb/python/python.c

@@ -32,8 +32,8 @@
 #include "serial.h"
 #include "readline/tilde.h"
 #include "python.h"
+#include "extension-priv.h"
 #include "cli/cli-utils.h"
-
 #include <ctype.h>
 
 /* Declared constants and enum for python stack printing.  */
@@ -56,6 +56,34 @@ static const char *const python_excp_enums[] =
    the default.  */
 static const char *gdbpy_should_print_stack = python_excp_message;
 
+#ifdef HAVE_PYTHON
+/* Forward decls, these are defined later.  */
+static const struct extension_language_script_ops python_extension_script_ops;
+static const struct extension_language_ops python_extension_ops;
+#endif
+
+/* The main struct describing GDB's interface to the Python
+   extension language.  */
+const struct extension_language_defn extension_language_python =
+{
+  EXT_LANG_PYTHON,
+  "python",
+  "Python",
+
+  ".py",
+  "-gdb.py",
+
+  python_control,
+
+#ifdef HAVE_PYTHON
+  &python_extension_script_ops,
+  &python_extension_ops
+#else
+  NULL,
+  NULL
+#endif
+};
+
 #ifdef HAVE_PYTHON
 
 #include "libiberty.h"
@@ -69,7 +97,6 @@ static const char *gdbpy_should_print_stack = python_excp_message;
 #include "version.h"
 #include "target.h"
 #include "gdbthread.h"
-#include "observer.h"
 #include "interps.h"
 #include "event-top.h"
 
@@ -104,6 +131,64 @@ PyObject *gdbpy_gdb_error;
 /* The `gdb.MemoryError' exception.  */
 PyObject *gdbpy_gdb_memory_error;
 
+static script_sourcer_func gdbpy_source_script;
+static objfile_script_sourcer_func gdbpy_source_objfile_script;
+static void gdbpy_finish_initialization
+  (const struct extension_language_defn *);
+static int gdbpy_initialized (const struct extension_language_defn *);
+static void gdbpy_eval_from_control_command
+  (const struct extension_language_defn *, struct command_line *cmd);
+static void gdbpy_start_type_printers (const struct extension_language_defn *,
+				       struct ext_lang_type_printers *);
+static enum ext_lang_rc gdbpy_apply_type_printers
+  (const struct extension_language_defn *,
+   const struct ext_lang_type_printers *, struct type *, char **);
+static void gdbpy_free_type_printers (const struct extension_language_defn *,
+				      struct ext_lang_type_printers *);
+static void gdbpy_clear_quit_flag (const struct extension_language_defn *);
+static void gdbpy_set_quit_flag (const struct extension_language_defn *);
+static int gdbpy_check_quit_flag (const struct extension_language_defn *);
+static enum ext_lang_rc gdbpy_before_prompt_hook
+  (const struct extension_language_defn *, const char *current_gdb_prompt);
+
+/* The interface between gdb proper and loading of python scripts.  */
+
+static const struct extension_language_script_ops python_extension_script_ops =
+{
+  gdbpy_source_script,
+  gdbpy_source_objfile_script,
+  gdbpy_auto_load_enabled
+};
+
+/* The interface between gdb proper and python extensions.  */
+
+static const struct extension_language_ops python_extension_ops =
+{
+  gdbpy_finish_initialization,
+  gdbpy_initialized,
+
+  gdbpy_eval_from_control_command,
+
+  gdbpy_start_type_printers,
+  gdbpy_apply_type_printers,
+  gdbpy_free_type_printers,
+
+  gdbpy_apply_val_pretty_printer,
+
+  gdbpy_apply_frame_filter,
+
+  gdbpy_preserve_values,
+
+  gdbpy_breakpoint_has_cond,
+  gdbpy_breakpoint_cond_says_stop,
+
+  gdbpy_clear_quit_flag,
+  gdbpy_set_quit_flag,
+  gdbpy_check_quit_flag,
+
+  gdbpy_before_prompt_hook
+};
+
 /* Architecture and language to be used in callbacks from
    the Python interpreter.  */
 struct gdbarch *python_gdbarch;
@@ -114,6 +199,7 @@ const struct language_defn *python_language;
 
 struct python_env
 {
+  struct active_ext_lang_state *previous_active;
   PyGILState_STATE state;
   struct gdbarch *gdbarch;
   const struct language_defn *language;
@@ -138,11 +224,17 @@ restore_python_env (void *p)
   PyGILState_Release (env->state);
   python_gdbarch = env->gdbarch;
   python_language = env->language;
+
+  restore_active_ext_lang (env->previous_active);
+
   xfree (env);
 }
 
 /* Called before entering the Python interpreter to install the
-   current language and architecture to be used for Python values.  */
+   current language and architecture to be used for Python values.
+   Also set the active extension language for GDB so that SIGINT's
+   are directed our way, and if necessary install the right SIGINT
+   handler.  */
 
 struct cleanup *
 ensure_python_env (struct gdbarch *gdbarch,
@@ -154,6 +246,8 @@ ensure_python_env (struct gdbarch *gdbarch,
   if (!gdb_python_initialized)
     error (_("Python not initialized"));
 
+  env->previous_active = set_active_ext_lang (&extension_language_python);
+
   env->state = PyGILState_Ensure ();
   env->gdbarch = python_gdbarch;
   env->language = python_language;
@@ -169,8 +263,8 @@ ensure_python_env (struct gdbarch *gdbarch,
 
 /* Clear the quit flag.  */
 
-void
-clear_quit_flag (void)
+static void
+gdbpy_clear_quit_flag (const struct extension_language_defn *extlang)
 {
   /* This clears the flag as a side effect.  */
   PyOS_InterruptOccurred ();
@@ -178,16 +272,16 @@ clear_quit_flag (void)
 
 /* Set the quit flag.  */
 
-void
-set_quit_flag (void)
+static void
+gdbpy_set_quit_flag (const struct extension_language_defn *extlang)
 {
   PyErr_SetInterrupt ();
 }
 
 /* Return true if the quit flag has been set, false otherwise.  */
 
-int
-check_quit_flag (void)
+static int
+gdbpy_check_quit_flag (const struct extension_language_defn *extlang)
 {
   return PyOS_InterruptOccurred ();
 }
@@ -343,8 +437,9 @@ compute_python_string (struct command_line *l)
 /* Take a command line structure representing a 'python' command, and
    evaluate its body using the Python interpreter.  */
 
-void
-eval_python_from_control_command (struct command_line *cmd)
+static void
+gdbpy_eval_from_control_command (const struct extension_language_defn *extlang,
+				 struct command_line *cmd)
 {
   int ret;
   char *script;
@@ -765,12 +860,14 @@ gdbpy_find_pc_line (PyObject *self, PyObject *args)
 }
 
 /* Read a file as Python code.
-   FILE is the file to run.  FILENAME is name of the file FILE.
+   This is the extension_language_script_ops.script_sourcer "method".
+   FILE is the file to load.  FILENAME is name of the file FILE.
    This does not throw any errors.  If an exception occurs python will print
    the traceback and clear the error indicator.  */
 
-void
-source_python_script (FILE *file, const char *filename)
+static void
+gdbpy_source_script (const struct extension_language_defn *extlang,
+		     FILE *file, const char *filename)
 {
   struct cleanup *cleanup;
 
@@ -899,14 +996,17 @@ gdbpy_initialize_events (void)
 
 
 
-static void
-before_prompt_hook (const char *current_gdb_prompt)
+/* This is the extension_language_ops.before_prompt "method".  */
+
+static enum ext_lang_rc
+gdbpy_before_prompt_hook (const struct extension_language_defn *extlang,
+			  const char *current_gdb_prompt)
 {
   struct cleanup *cleanup;
   char *prompt = NULL;
 
   if (!gdb_python_initialized)
-    return;
+    return EXT_LANG_RC_NOP;
 
   cleanup = ensure_python_env (get_current_arch (), current_language);
 
@@ -968,12 +1068,12 @@ before_prompt_hook (const char *current_gdb_prompt)
     set_prompt (prompt);
 
   do_cleanups (cleanup);
-  return;
+  return prompt != NULL ? EXT_LANG_RC_OK : EXT_LANG_RC_NOP;
 
  fail:
   gdbpy_print_stack ();
   do_cleanups (cleanup);
-  return;
+  return EXT_LANG_RC_ERROR;
 }
 
 
@@ -1158,16 +1258,19 @@ gdbpy_progspaces (PyObject *unused1, PyObject *unused2)
 
 /* The "current" objfile.  This is set when gdb detects that a new
    objfile has been loaded.  It is only set for the duration of a call to
-   source_python_script_for_objfile; it is NULL at other times.  */
+   gdbpy_source_objfile_script; it is NULL at other times.  */
 static struct objfile *gdbpy_current_objfile;
 
 /* Set the current objfile to OBJFILE and then read FILE named FILENAME
    as Python code.  This does not throw any errors.  If an exception
-   occurs python will print the traceback and clear the error indicator.  */
+   occurs python will print the traceback and clear the error indicator.
+   This is the extension_language_script_ops.objfile_script_sourcer
+   "method".  */
 
-void
-source_python_script_for_objfile (struct objfile *objfile, FILE *file,
-                                  const char *filename)
+static void
+gdbpy_source_objfile_script (const struct extension_language_defn *extlang,
+			     struct objfile *objfile, FILE *file,
+			     const char *filename)
 {
   struct cleanup *cleanups;
 
@@ -1225,18 +1328,20 @@ gdbpy_objfiles (PyObject *unused1, PyObject *unused2)
   return list;
 }
 
-/* Compute the list of active type printers and return it.  The result
-   of this function can be passed to apply_type_printers, and should
-   be freed by free_type_printers.  */
+/* Compute the list of active python type printers and store them in
+   EXT_PRINTERS->py_type_printers.  The product of this function is used by
+   gdbpy_apply_type_printers, and freed by gdbpy_free_type_printers.
+   This is the extension_language_ops.start_type_printers "method".  */
 
-void *
-start_type_printers (void)
+static void
+gdbpy_start_type_printers (const struct extension_language_defn *extlang,
+			   struct ext_lang_type_printers *ext_printers)
 {
   struct cleanup *cleanups;
-  PyObject *type_module, *func = NULL, *result_obj = NULL;
+  PyObject *type_module, *func = NULL, *printers_obj = NULL;
 
   if (!gdb_python_initialized)
-    return NULL;
+    return;
 
   cleanups = ensure_python_env (get_current_arch (), current_language);
 
@@ -1254,39 +1359,41 @@ start_type_printers (void)
       goto done;
     }
 
-  result_obj = PyObject_CallFunctionObjArgs (func, (char *) NULL);
-  if (result_obj == NULL)
+  printers_obj = PyObject_CallFunctionObjArgs (func, (char *) NULL);
+  if (printers_obj == NULL)
     gdbpy_print_stack ();
+  else
+    ext_printers->py_type_printers = printers_obj;
 
  done:
   Py_XDECREF (type_module);
   Py_XDECREF (func);
   do_cleanups (cleanups);
-  return result_obj;
 }
 
-/* If TYPE is recognized by some type printer, return a newly
-   allocated string holding the type's replacement name.  The caller
-   is responsible for freeing the string.  Otherwise, return NULL.
+/* If TYPE is recognized by some type printer, store in *PRETTIED_TYPE
+   a newly allocated string holding the type's replacement name, and return
+   EXT_LANG_RC_OK.  The caller is responsible for freeing the string.
+   If there's a Python error return EXT_LANG_RC_ERROR.
+   Otherwise, return EXT_LANG_RC_NOP.
+   This is the extension_language_ops.apply_type_printers "method".  */
 
-   This function has a bit of a funny name, since it actually applies
-   recognizers, but this seemed clearer given the start_type_printers
-   and free_type_printers functions.  */
-
-char *
-apply_type_printers (void *printers, struct type *type)
+static enum ext_lang_rc
+gdbpy_apply_type_printers (const struct extension_language_defn *extlang,
+			   const struct ext_lang_type_printers *ext_printers,
+			   struct type *type, char **prettied_type)
 {
   struct cleanup *cleanups;
   PyObject *type_obj, *type_module = NULL, *func = NULL;
   PyObject *result_obj = NULL;
-  PyObject *printers_obj = printers;
+  PyObject *printers_obj = ext_printers->py_type_printers;
   char *result = NULL;
 
   if (printers_obj == NULL)
-    return NULL;
+    return EXT_LANG_RC_NOP;
 
   if (!gdb_python_initialized)
-    return NULL;
+    return EXT_LANG_RC_NOP;
 
   cleanups = ensure_python_env (get_current_arch (), current_language);
 
@@ -1332,16 +1439,20 @@ apply_type_printers (void *printers, struct type *type)
   Py_XDECREF (func);
   Py_XDECREF (result_obj);
   do_cleanups (cleanups);
-  return result;
+  if (result != NULL)
+    *prettied_type = result;
+  return result != NULL ? EXT_LANG_RC_OK : EXT_LANG_RC_ERROR;
 }
 
-/* Free the result of start_type_printers.  */
+/* Free the result of start_type_printers.
+   This is the extension_language_ops.free_type_printers "method".  */
 
-void
-free_type_printers (void *arg)
+static void
+gdbpy_free_type_printers (const struct extension_language_defn *extlang,
+			  struct ext_lang_type_printers *ext_printers)
 {
   struct cleanup *cleanups;
-  PyObject *printers = arg;
+  PyObject *printers = ext_printers->py_type_printers;
 
   if (printers == NULL)
     return;
@@ -1381,62 +1492,6 @@ python_command (char *arg, int from_tty)
   python_interactive_command (arg, from_tty);
 }
 
-void
-eval_python_from_control_command (struct command_line *cmd)
-{
-  error (_("Python scripting is not supported in this copy of GDB."));
-}
-
-void
-source_python_script (FILE *file, const char *filename)
-{
-  internal_error (__FILE__, __LINE__,
-		  _("source_python_script called when Python scripting is "
-		    "not supported."));
-}
-
-int
-gdbpy_should_stop (struct gdbpy_breakpoint_object *bp_obj)
-{
-  internal_error (__FILE__, __LINE__,
-		  _("gdbpy_should_stop called when Python scripting is  " \
-		    "not supported."));
-}
-
-int
-gdbpy_breakpoint_has_py_cond (struct gdbpy_breakpoint_object *bp_obj)
-{
-  internal_error (__FILE__, __LINE__,
-		  _("gdbpy_breakpoint_has_py_cond called when Python " \
-		    "scripting is not supported."));
-}
-
-void *
-start_type_printers (void)
-{
-  return NULL;
-}
-
-char *
-apply_type_printers (void *ignore, struct type *type)
-{
-  return NULL;
-}
-
-void
-free_type_printers (void *arg)
-{
-}
-
-enum py_bt_status
-apply_frame_filter (struct frame_info *frame, int flags,
-		    enum py_frame_args args_type,
-		    struct ui_out *out, int frame_low,
-		    int frame_high)
-{
-  return PY_BT_NO_FILTERS;
-}
-
 #endif /* HAVE_PYTHON */
 
 
@@ -1473,16 +1528,25 @@ user_show_python (char *args, int from_tty)
 static void
 finalize_python (void *ignore)
 {
+  struct active_ext_lang_state *previous_active;
+
   /* We don't use ensure_python_env here because if we ever ran the
      cleanup, gdb would crash -- because the cleanup calls into the
      Python interpreter, which we are about to destroy.  It seems
      clearer to make the needed calls explicitly here than to create a
      cleanup and then mysteriously discard it.  */
+
+  /* This is only called as a final cleanup so we can assume the active
+     SIGINT handler is gdb's.  We still need to tell it to notify Python.  */
+  previous_active = set_active_ext_lang (&extension_language_python);
+
   (void) PyGILState_Ensure ();
   python_gdbarch = target_gdbarch ();
   python_language = current_language;
 
   Py_Finalize ();
+
+  restore_active_ext_lang (previous_active);
 }
 #endif
 
@@ -1691,8 +1755,6 @@ message == an error message without a stack will be printed."),
       || gdbpy_initialize_arch () < 0)
     goto fail;
 
-  observer_attach_before_prompt (before_prompt_hook);
-
   gdbpy_to_string_cst = PyString_FromString ("to_string");
   if (gdbpy_to_string_cst == NULL)
     goto fail;
@@ -1734,10 +1796,11 @@ message == an error message without a stack will be printed."),
 /* Perform the remaining python initializations.
    These must be done after GDB is at least mostly initialized.
    E.g., The "info pretty-printer" command needs the "info" prefix
-   command installed.  */
+   command installed.
+   This is the extension_language_ops.finish_initialization "method".  */
 
-void
-finish_python_initialization (void)
+static void
+gdbpy_finish_initialization (const struct extension_language_defn *extlang)
 {
   PyObject *m;
   char *gdb_pythondir;
@@ -1816,6 +1879,15 @@ finish_python_initialization (void)
   do_cleanups (cleanup);
 }
 
+/* Return non-zero if Python has successfully initialized.
+   This is the extension_languages_ops.initialized "method".  */
+
+static int
+gdbpy_initialized (const struct extension_language_defn *extlang)
+{
+  return gdb_python_initialized;
+}
+
 #endif /* HAVE_PYTHON */