[python] allow set- and show- specific help for Parameters

[Tom Tromey <tromey at redhat dot com>]

This changes the Parameter code to allow set- and show-specific help.

I also made a new "_cst" global and fixed the *_object_type
initializers.

Tom

2008-11-18  Tom Tromey  <tromey@redhat.com>

	* python/python-internal.h (gdbpy_doc_cst): Declare.
	* python/python-cmd.c (cmdpy_init): Use gdbpy_doc_cst.  Don't set
	tp_new or tp_init.
	(cmdpy_object_type): Add extra entries.  Set tp_init and tp_new.
	* python/python.c (gdbpy_doc_cst): New global.
	(_initialize_python): Initialize it.
	* python/python-param.c (set_doc_cst, show_doc_cst): New globals.
	(gdbpy_initialize_parameters): Initialize them.  Don't set
	tp_new or tp_init.
	(parmpy_init): Use gdbpy_doc_cst.  Get set and show help.  Don't
	examine __doc__.
	(get_doc_string): New function.
	(parmpy_object_type): Add extra entries.  Set tp_init and tp_new.

2008-11-18  Tom Tromey  <tromey@redhat.com>

	* gdb.texinfo (Parameters In Python): Document set_doc, show_doc.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index eb24ece..9446ce4 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -18553,6 +18553,20 @@ documentation string for the parameter's class, if there is one.  If
 there is no documentation string, a default value is used.
 @end defmethod
 
+@defivar Parameter set_doc
+If this attribute exists, and is a string, then its value is used as
+the help text for this parameter's @code{set} command.  The value is
+examined when @code{Parameter.__init__} is invoked; subsequent changes
+have no effect.
+@end defivar
+
+@defivar Parameter show_doc
+If this attribute exists, and is a string, then its value is used as
+the help text for this parameter's @code{show} command.  The value is
+examined when @code{Parameter.__init__} is invoked; subsequent changes
+have no effect.
+@end defivar
+
 @defivar Parameter value
 The @code{value} attribute holds the underlying value of the
 parameter.  It can be read and assigned to just as any other
diff --git a/gdb/python/python-cmd.c b/gdb/python/python-cmd.c
index 63b5432..91cdc7f 100644
--- a/gdb/python/python-cmd.c
+++ b/gdb/python/python-cmd.c
@@ -389,9 +389,9 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   if (! cmd_name)
     return -1;
 
-  if (PyObject_HasAttrString (self, "__doc__"))
+  if (PyObject_HasAttr (self, gdbpy_doc_cst))
     {
-      PyObject *ds_obj = PyObject_GetAttrString (self, "__doc__");
+      PyObject *ds_obj = PyObject_GetAttr (self, gdbpy_doc_cst);
       if (ds_obj && gdbpy_is_string (ds_obj))
 	docstring = python_string_to_host_string (ds_obj);
     }
@@ -437,8 +437,6 @@ gdbpy_initialize_commands (void)
 {
   int i;
 
-  cmdpy_object_type.tp_new = PyType_GenericNew;
-  cmdpy_object_type.tp_init = cmdpy_init;
   if (PyType_Ready (&cmdpy_object_type) < 0)
     return;
 
@@ -515,5 +513,15 @@ static PyTypeObject cmdpy_object_type =
   0,				  /* tp_weaklistoffset */
   0,				  /* tp_iter */
   0,				  /* tp_iternext */
-  cmdpy_object_methods		  /* tp_methods */
+  cmdpy_object_methods,		  /* tp_methods */
+  0,				  /* tp_members */
+  0,				  /* tp_getset */
+  0,				  /* tp_base */
+  0,				  /* tp_dict */
+  0,				  /* tp_descr_get */
+  0,				  /* tp_descr_set */
+  0,				  /* tp_dictoffset */
+  cmdpy_init,			  /* tp_init */
+  0,				  /* tp_alloc */
+  PyType_GenericNew		  /* tp_new */
 };
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index 19f39cb..a03d889 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -136,5 +136,6 @@ char *gdbpy_get_display_hint (PyObject *printer);
 extern PyObject *gdbpy_children_cst;
 extern PyObject *gdbpy_to_string_cst;
 extern PyObject *gdbpy_display_hint_cst;
+extern PyObject *gdbpy_doc_cst;
 
 #endif /* GDB_PYTHON_INTERNAL_H */
diff --git a/gdb/python/python-param.c b/gdb/python/python-param.c
index cf1ceaa..96c92c8 100644
--- a/gdb/python/python-param.c
+++ b/gdb/python/python-param.c
@@ -89,6 +89,10 @@ typedef struct parmpy_object parmpy_object;
 
 static PyTypeObject parmpy_object_type;
 
+/* Some handy string constants.  */
+static PyObject *set_doc_cst;
+static PyObject *show_doc_cst;
+
 
 
 /* Get an attribute.  */
@@ -374,6 +378,23 @@ compute_enum_values (parmpy_object *self, PyObject *enum_values)
   return 1;
 }
 
+/* A helper function which returns a documentation string for an
+   object.  */
+static char *
+get_doc_string (PyObject *object, PyObject *attr)
+{
+  char *result = NULL;
+  if (PyObject_HasAttr (object, attr))
+    {
+      PyObject *ds_obj = PyObject_GetAttr (object, attr);
+      if (ds_obj && gdbpy_is_string (ds_obj))
+	result = python_string_to_host_string (ds_obj);
+    }
+  if (! result)
+    result = xstrdup ("This command is not documented.");
+  return result;
+}
+
 /* Object initializer; sets up gdb-side structures for command.
 
    Use: __init__(NAME, CMDCLASS, PARMCLASS, [ENUM])
@@ -401,7 +422,7 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
 {
   parmpy_object *obj = (parmpy_object *) self;
   char *name;
-  char *docstring = NULL;
+  char *set_doc, *show_doc;
   char *cmd_name;
   int parmclass, cmdtype;
   PyObject *enum_values = NULL;
@@ -458,15 +479,10 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   if (! cmd_name)
     return -1;
 
-  /* FIXME: need set and show docs.  */
-  if (PyObject_HasAttrString (self, "__doc__"))
-    {
-      PyObject *ds_obj = PyObject_GetAttrString (self, "__doc__");
-      if (ds_obj && gdbpy_is_string (ds_obj))
-	docstring = python_string_to_host_string (ds_obj);
-    }
-  if (! docstring)
-    docstring = xstrdup ("This command is not documented.");
+  /* FIXME: there is no way to register a destructor function for
+     set/show commands.  So, these are leaked.  */
+  set_doc = get_doc_string (self, set_doc_cst);
+  show_doc = get_doc_string (self, show_doc_cst);
 
   Py_INCREF (self);
 
@@ -474,13 +490,14 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
     {
       add_setshow_generic (parmclass, (enum command_class) cmdtype,
 			   cmd_name, obj,
-			   "FIXME: set doc", "FIXME: show doc",
-			   docstring, set_list, show_list);
+			   set_doc, show_doc,
+			   NULL, set_list, show_list);
     }
   if (except.reason < 0)
     {
       xfree (cmd_name);
-      xfree (docstring);
+      xfree (set_doc);
+      xfree (show_doc);
       Py_DECREF (self);
       PyErr_Format (except.reason == RETURN_QUIT
 		    ? PyExc_KeyboardInterrupt : PyExc_RuntimeError,
@@ -498,11 +515,16 @@ gdbpy_initialize_parameters (void)
 {
   int i;
 
-  parmpy_object_type.tp_new = PyType_GenericNew;
-  parmpy_object_type.tp_init = parmpy_init;
   if (PyType_Ready (&parmpy_object_type) < 0)
     return;
 
+  set_doc_cst = PyString_FromString ("set_doc");
+  if (! set_doc_cst)
+    return;
+  show_doc_cst = PyString_FromString ("show_doc");
+  if (! show_doc_cst)
+    return;
+
   for (i = 0; parm_constants[i].name; ++i)
     {
       if (PyModule_AddIntConstant (gdb_module,
@@ -548,5 +570,15 @@ static PyTypeObject parmpy_object_type =
   0,				  /* tp_weaklistoffset */
   0,				  /* tp_iter */
   0,				  /* tp_iternext */
-  0				  /* tp_methods */
+  0,				  /* tp_methods */
+  0,				  /* tp_members */
+  0,				  /* tp_getset */
+  0,				  /* tp_base */
+  0,				  /* tp_dict */
+  0,				  /* tp_descr_get */
+  0,				  /* tp_descr_set */
+  0,				  /* tp_dictoffset */
+  parmpy_init,			  /* tp_init */
+  0,				  /* tp_alloc */
+  PyType_GenericNew		  /* tp_new */
 };
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 1ff3c25..340213f 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -66,6 +66,7 @@ PyObject *gdb_module;
 PyObject *gdbpy_to_string_cst;
 PyObject *gdbpy_children_cst;
 PyObject *gdbpy_display_hint_cst;
+PyObject *gdbpy_doc_cst;
 
 /* Given a command_line, return a command string suitable for passing
    to Python.  Lines in the string are separated by newlines.  The
@@ -1276,6 +1277,7 @@ Enables or disables auto-loading of Python code when an object is opened."),
   gdbpy_to_string_cst = PyString_FromString ("to_string");
   gdbpy_children_cst = PyString_FromString ("children");
   gdbpy_display_hint_cst = PyString_FromString ("display_hint");
+  gdbpy_doc_cst = PyString_FromString ("__doc__");
 
   /* Create a couple objects which are used for Python's stdout and
      stderr.  */