Use generic attribute management in PL/Python

Switch the implementation of the plan and result types to generic attribute
management, as described at <http://docs.python.org/extending/newtypes.html>.
This modernizes and simplifies the code a bit and prepares for Python 3.1,
where the old way doesn't work anymore.

src/pl/plpython/expected/plpython_spi.out

@@ -111,3 +111,24 @@ SELECT join_sequences(sequences) FROM sequences
 ----------------
 (0 rows)
 
+--
+-- plan and result objects
+--
+CREATE FUNCTION result_nrows_test() RETURNS int
+AS $$
+plan = plpy.prepare("SELECT 1 UNION SELECT 2")
+plpy.info(plan.status()) # not really documented or useful
+result = plpy.execute(plan)
+if result.status() > 0:
+   return result.nrows()
+else:
+   return None
+$$ LANGUAGE plpythonu;
+SELECT result_nrows_test();
+INFO:  (True,)
+CONTEXT:  PL/Python function "result_nrows_test"
+ result_nrows_test 
+-------------------
+                 2
+(1 row)
+

src/pl/plpython/plpython.c

 /**********************************************************************
  * plpython.c - python as a procedural language for PostgreSQL
  *
- *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.125 2009/08/14 13:12:21 petere Exp $
+ *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.126 2009/08/25 08:14:42 petere Exp $
  *
  *********************************************************************
  */
@@ -2050,12 +2050,10 @@ static PyObject *PLy_fatal(PyObject *, PyObject *);
 #define is_PLyPlanObject(x) ((x)->ob_type == &PLy_PlanType)
 static PyObject *PLy_plan_new(void);
 static void PLy_plan_dealloc(PyObject *);
-static PyObject *PLy_plan_getattr(PyObject *, char *);
 static PyObject *PLy_plan_status(PyObject *, PyObject *);
 
 static PyObject *PLy_result_new(void);
 static void PLy_result_dealloc(PyObject *);
-static PyObject *PLy_result_getattr(PyObject *, char *);
 static PyObject *PLy_result_nrows(PyObject *, PyObject *);
 static PyObject *PLy_result_status(PyObject *, PyObject *);
 static Py_ssize_t PLy_result_length(PyObject *);
@@ -2072,6 +2070,11 @@ static PyObject *PLy_spi_execute_plan(PyObject *, PyObject *, long);
 static PyObject *PLy_spi_execute_fetch_result(SPITupleTable *, int, int);
 
 
+static PyMethodDef PLy_plan_methods[] = {
+	{"status", PLy_plan_status, METH_VARARGS, NULL},
+	{NULL, NULL, 0, NULL}
+};
+
 static PyTypeObject PLy_PlanType = {
 	PyObject_HEAD_INIT(NULL)
 	0,							/* ob_size */
@@ -2084,7 +2087,7 @@ static PyTypeObject PLy_PlanType = {
 	 */
 	PLy_plan_dealloc,			/* tp_dealloc */
 	0,							/* tp_print */
-	PLy_plan_getattr,			/* tp_getattr */
+	0,							/* tp_getattr */
 	0,							/* tp_setattr */
 	0,							/* tp_compare */
 	0,							/* tp_repr */
@@ -2099,11 +2102,13 @@ static PyTypeObject PLy_PlanType = {
 	0,							/* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,	/* tp_flags */
 	PLy_plan_doc,				/* tp_doc */
-};
-
-static PyMethodDef PLy_plan_methods[] = {
-	{"status", PLy_plan_status, METH_VARARGS, NULL},
-	{NULL, NULL, 0, NULL}
+	0,							/* tp_traverse */
+	0,							/* tp_clear */
+	0,							/* tp_richcompare */
+	0,							/* tp_weaklistoffset */
+	0,							/* tp_iter */
+	0,							/* tp_iternext */
+	PLy_plan_methods,			/* tp_tpmethods */
 };
 
 static PySequenceMethods PLy_result_as_sequence = {
@@ -2116,6 +2121,12 @@ static PySequenceMethods PLy_result_as_sequence = {
 	PLy_result_ass_slice,		/* sq_ass_slice */
 };
 
+static PyMethodDef PLy_result_methods[] = {
+	{"nrows", PLy_result_nrows, METH_VARARGS, NULL},
+	{"status", PLy_result_status, METH_VARARGS, NULL},
+	{NULL, NULL, 0, NULL}
+};
+
 static PyTypeObject PLy_ResultType = {
 	PyObject_HEAD_INIT(NULL)
 	0,							/* ob_size */
@@ -2128,7 +2139,7 @@ static PyTypeObject PLy_ResultType = {
 	 */
 	PLy_result_dealloc,			/* tp_dealloc */
 	0,							/* tp_print */
-	PLy_result_getattr,			/* tp_getattr */
+	0,							/* tp_getattr */
 	0,							/* tp_setattr */
 	0,							/* tp_compare */
 	0,							/* tp_repr */
@@ -2143,12 +2154,13 @@ static PyTypeObject PLy_ResultType = {
 	0,							/* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,	/* tp_flags */
 	PLy_result_doc,				/* tp_doc */
-};
-
-static PyMethodDef PLy_result_methods[] = {
-	{"nrows", PLy_result_nrows, METH_VARARGS, NULL},
-	{"status", PLy_result_status, METH_VARARGS, NULL},
-	{NULL, NULL, 0, NULL}
+	0,							/* tp_traverse */
+	0,							/* tp_clear */
+	0,							/* tp_richcompare */
+	0,							/* tp_weaklistoffset */
+	0,							/* tp_iter */
+	0,							/* tp_iternext */
+	PLy_result_methods,			/* tp_tpmethods */
 };
 
 static PyMethodDef PLy_methods[] = {
@@ -2217,12 +2229,6 @@ PLy_plan_dealloc(PyObject *arg)
 }
 
 
-static PyObject *
-PLy_plan_getattr(PyObject *self, char *name)
-{
-	return Py_FindMethod(PLy_plan_methods, self, name);
-}
-
 static PyObject *
 PLy_plan_status(PyObject *self, PyObject *args)
 {
@@ -2270,12 +2276,6 @@ PLy_result_dealloc(PyObject *arg)
 	arg->ob_type->tp_free(arg);
 }
 
-static PyObject *
-PLy_result_getattr(PyObject *self, char *name)
-{
-	return Py_FindMethod(PLy_result_methods, self, name);
-}
-
 static PyObject *
 PLy_result_nrows(PyObject *self, PyObject *args)
 {

src/pl/plpython/sql/plpython_spi.sql

@@ -87,3 +87,21 @@ SELECT join_sequences(sequences) FROM sequences
 	WHERE join_sequences(sequences) ~* '^A';
 SELECT join_sequences(sequences) FROM sequences
 	WHERE join_sequences(sequences) ~* '^B';
+
+
+--
+-- plan and result objects
+--
+
+CREATE FUNCTION result_nrows_test() RETURNS int
+AS $$
+plan = plpy.prepare("SELECT 1 UNION SELECT 2")
+plpy.info(plan.status()) # not really documented or useful
+result = plpy.execute(plan)
+if result.status() > 0:
+   return result.nrows()
+else:
+   return None
+$$ LANGUAGE plpythonu;
+
+SELECT result_nrows_test();