[PATCH, doc RFA] Add ability to set random attributes in python objfiles,progspaces

[Doug Evans <dje at google dot com>]

Hi.

I have a need to do some extra record keeping in progspaces and
objfiles.  This patch adds the ability to add random attributes
to objfile and progspace objects using the same mechanism used
for gdb.Fields.

Regression tested on amd64-linux.

2014-10-09  Doug Evans  <dje@google.com>

	* NEWS: Mention ability add attributes to gdb.Objfile and
	gdb.Progspace objects.
	* python/py-objfile.c (objfile_object): New member dict.
	(objfpy_dealloc): Py_XDECREF dict.
	(objfpy_initialize): Initialize dict.
	(objfile_getset): Add __dict__.
	(objfile_object_type): Set tp_dictoffset member.
	* python/py-progspace.c (progspace_object): New member dict.
	(pspy_dealloc): Py_XDECREF dict.
	(pspy_initialize): Initialize dict.
	(pspace_getset): Add __dict__.
	(pspace_object_type): Set tp_dictoffset member.

	doc/
	* gdb.texinfo (Progspaces In Python): Document ability to add
	random attributes to gdb.Progspace objects.
	(Objfiles In Python): Document ability to add random attributes to
	gdb.objfile objects.

	testsuite/
	* gdb.python/py-objfile.exp: Add tests for setting random attributes
	in objfiles.
	* gdb.python/py-progspace.exp: Add tests for setting random attributes
	in progspaces.

diff --git a/gdb/NEWS b/gdb/NEWS
index b56fe8e..ec43a22 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -9,6 +9,7 @@
 
   ** You can now access frame registers from Python scripts.
   ** New attribute 'producer' for gdb.Symtab objects.
+  ** You can now add attributes to gdb.Objfile and gdb.Progspace objects.
 
 * New Python-based convenience functions:
 
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 81ec11b..14a2181 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -3356,6 +3356,10 @@ The @code{frame_filters} attribute is a dictionary of frame filter
 objects.  @xref{Frame Filter API}, for more information.
 @end defvar
 
+One may add arbitrary attributes to @code{gdb.Progspace} objects.
+This is useful if for example one needs to do some extra record keeping
+associated with the progspace.
+
 @node Objfiles In Python
 @subsubsection Objfiles In Python
 
@@ -3411,6 +3415,26 @@ The @code{frame_filters} attribute is a dictionary of frame filter
 objects.  @xref{Frame Filter API}, for more information.
 @end defvar
 
+One may add arbitrary attributes to @code{gdb.Objfile} objects.
+This is useful if for example one needs to do some extra record keeping
+associated with the objfile.
+
+In this contrived example we record the time when @value{GDBN}
+loaded the objfile.
+
+@smallexample
+(gdb) python
+import datetime
+def new_objfile_handler (event):
+    event.new_objfile.time_loaded = datetime.datetime.today ()
+gdb.events.new_objfile.connect (new_objfile_handler)
+end
+(gdb) file ./hello
+Reading symbols from ./hello...done.
+(gdb) python print gdb.objfiles()[0].time_loaded
+2014-10-09 11:41:36.770345
+@end smallexample
+
 A @code{gdb.Objfile} object has the following methods:
 
 @defun Objfile.is_valid ()
diff --git a/gdb/python/py-objfile.c b/gdb/python/py-objfile.c
index df29691..32bceee 100644
--- a/gdb/python/py-objfile.c
+++ b/gdb/python/py-objfile.c
@@ -30,6 +30,9 @@ typedef struct
   /* The corresponding objfile.  */
   struct objfile *objfile;
 
+  /* Dictionary holding user-added attributes.  */
+  PyObject *dict;
+
   /* The pretty-printer list of functions.  */
   PyObject *printers;
 
@@ -67,6 +70,7 @@ objfpy_dealloc (PyObject *o)
 {
   objfile_object *self = (objfile_object *) o;
 
+  Py_XDECREF (self->dict);
   Py_XDECREF (self->printers);
   Py_XDECREF (self->frame_filters);
   Py_XDECREF (self->type_printers);
@@ -81,6 +85,7 @@ static int
 objfpy_initialize (objfile_object *self)
 {
   self->objfile = NULL;
+  self->dict = NULL;
 
   self->printers = PyList_New (0);
   if (self->printers == NULL)
@@ -336,6 +341,8 @@ Return true if this object file is valid, false if not." },
 
 static PyGetSetDef objfile_getset[] =
 {
+  { "__dict__", gdb_py_generic_dict, NULL,
+    "The __dict__ for this objfile.", &objfile_object_type },
   { "filename", objfpy_get_filename, NULL,
     "The objfile's filename, or None.", NULL },
   { "pretty_printers", objfpy_get_printers, objfpy_set_printers,
@@ -385,7 +392,7 @@ static PyTypeObject objfile_object_type =
   0,				  /* tp_dict */
   0,				  /* tp_descr_get */
   0,				  /* tp_descr_set */
-  0,				  /* tp_dictoffset */
+  offsetof (objfile_object, dict), /* tp_dictoffset */
   0,				  /* tp_init */
   0,				  /* tp_alloc */
   objfpy_new,			  /* tp_new */
diff --git a/gdb/python/py-progspace.c b/gdb/python/py-progspace.c
index 4280032..72ed353 100644
--- a/gdb/python/py-progspace.c
+++ b/gdb/python/py-progspace.c
@@ -32,6 +32,9 @@ typedef struct
   /* The corresponding pspace.  */
   struct program_space *pspace;
 
+  /* Dictionary holding user-added attributes.  */
+  PyObject *dict;
+
   /* The pretty-printer list of functions.  */
   PyObject *printers;
 
@@ -75,6 +78,7 @@ pspy_dealloc (PyObject *self)
 {
   pspace_object *ps_self = (pspace_object *) self;
 
+  Py_XDECREF (ps_self->dict);
   Py_XDECREF (ps_self->printers);
   Py_XDECREF (ps_self->frame_filters);
   Py_XDECREF (ps_self->type_printers);
@@ -89,6 +93,7 @@ static int
 pspy_initialize (pspace_object *self)
 {
   self->pspace = NULL;
+  self->dict = NULL;
 
   self->printers = PyList_New (0);
   if (self->printers == NULL)
@@ -331,6 +336,8 @@ gdbpy_initialize_pspace (void)
 
 static PyGetSetDef pspace_getset[] =
 {
+  { "__dict__", gdb_py_generic_dict, NULL,
+    "The __dict__ for this progspace.", &pspace_object_type },
   { "filename", pspy_get_filename, NULL,
     "The progspace's main filename, or None.", NULL },
   { "pretty_printers", pspy_get_printers, pspy_set_printers,
@@ -380,7 +387,7 @@ static PyTypeObject pspace_object_type =
   0,				  /* tp_dict */
   0,				  /* tp_descr_get */
   0,				  /* tp_descr_set */
-  0,				  /* tp_dictoffset */
+  offsetof (pspace_object, dict), /* tp_dictoffset */
   0,				  /* tp_init */
   0,				  /* tp_alloc */
   pspy_new,			  /* tp_new */
diff --git a/gdb/testsuite/gdb.python/py-objfile.exp b/gdb/testsuite/gdb.python/py-objfile.exp
index 56f99f8..d880da3 100644
--- a/gdb/testsuite/gdb.python/py-objfile.exp
+++ b/gdb/testsuite/gdb.python/py-objfile.exp
@@ -44,3 +44,8 @@ gdb_test "python print (objfile.is_valid())" "True" \
 gdb_unload
 gdb_test "python print (objfile.is_valid())" "False" \
   "Get objfile validity after unload"
+
+gdb_py_test_silent_cmd "python objfile.random_attribute = 42" \
+    "Set random attribute in objfile" 1
+gdb_test "python print (objfile.random_attribute)" "42" \
+    "Verify set of random attribute in objfile"
diff --git a/gdb/testsuite/gdb.python/py-progspace.exp b/gdb/testsuite/gdb.python/py-progspace.exp
index 2fcfdb9..a47fae6 100644
--- a/gdb/testsuite/gdb.python/py-progspace.exp
+++ b/gdb/testsuite/gdb.python/py-progspace.exp
@@ -16,6 +16,8 @@
 # This file is part of the GDB testsuite.  It tests the program space
 # support in Python.
 
+load_lib gdb-python.exp
+
 standard_testfile
 
 if {[build_executable $testfile.exp $testfile $srcfile debug] == -1} {
@@ -37,5 +39,13 @@ gdb_test "python print (gdb.progspaces())" "\\\[<gdb.Progspace object at $hex>\\
 
 gdb_load ${binfile}
 
-gdb_test "python print (gdb.current_progspace().filename)" "py-progspace" \
+gdb_py_test_silent_cmd "python progspace = gdb.current_progspace()" \
+    "Get current progspace" 1
+
+gdb_test "python print (progspace.filename)" "py-progspace" \
   "current progspace filename (py-progspace)"
+
+gdb_py_test_silent_cmd "python progspace.random_attribute = 42" \
+    "Set random attribute in progspace" 1
+gdb_test "python print (progspace.random_attribute)" "42" \
+    "Verify set of random attribute in progspace"