[PATCH 3/8] python: allow callback function to be a class method

[Arend van Spriel]

The callback functionality only worked for regular Python
functions. With this patch it also allows the callback
to be a class method (bounded or unbounded) as show in
example below.

class test_class(object):
	def my_callback(self, msg, arg):
		print('handling %s' % str(msg))

s = netlink.core.Socket()
testobj = test_class()
netlink.capi.py_nl_cb_set(cb, netlink.capi.NL_CB_VALID,
			  netlink.capi.NL_CB_CUSTOM,
			  test_class.my_callback, testobj)
netlink.capi.py_nl_cb_err(cb, netlink.capi.NL_CB_CUSTOM,
                          test_class.my_callback, s)

Signed-off-by: Arend van Spriel <arend at broadcom.com>
---
 python/netlink/capi.i |   32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/python/netlink/capi.i b/python/netlink/capi.i
index 785e0a6..507c220 100644
--- a/python/netlink/capi.i
+++ b/python/netlink/capi.i
@@ -9,6 +9,7 @@
 #include <netlink/attr.h>
 #include <net/if.h>
 
+#define DEBUG
 #include "utils.h"
 %}
 
@@ -613,14 +614,27 @@ static int nl_recv_msg_handler(struct nl_msg *msg, void *arg)
 	PyObject *msgobj;
 	PyObject *cbparobj;
 	PyObject *resobj;
+	PyObject *funcobj;
 	int result;
 
 	if (!cbd)
 		return NL_STOP;
 	msgobj = SWIG_NewPointerObj(SWIG_as_voidptr(msg),
 				    SWIGTYPE_p_nl_msg, 0 |  0 );
-	cbparobj = Py_BuildValue("(OO)", msgobj, cbd->cba);
-	resobj = PyObject_CallObject(cbd->cbf, cbparobj);
+	/* add selfobj if callback is a method */
+	if (cbd->cbf && PyMethod_Check(cbd->cbf)) {
+		PyObject *selfobj = PyMethod_Self(cbd->cbf);
+		cbparobj = Py_BuildValue("(OOO)", selfobj ? selfobj : cbd->cba,
+					 msgobj, cbd->cba);
+		funcobj = PyMethod_Function(cbd->cbf);
+		pynl_dbg("callback %sbounded instance method %p\n",
+			 selfobj ? "" : "un", funcobj);
+	} else {
+		cbparobj = Py_BuildValue("(OO)", msgobj, cbd->cba);
+		funcobj = cbd->cbf;
+		pynl_dbg("callback function %p\n", funcobj);
+	}
+	resobj = PyObject_CallObject(funcobj, cbparobj);
 	Py_DECREF(cbparobj);
 	if (resobj == NULL)
 		return NL_STOP;
@@ -637,14 +651,24 @@ static int nl_recv_err_handler(struct sockaddr_nl *nla, struct nlmsgerr *err,
 	PyObject *errobj;
 	PyObject *cbparobj;
 	PyObject *resobj;
+	PyObject *funcobj;
 	int result;
 
 	if (!cbd)
 		return NL_STOP;
 	errobj = SWIG_NewPointerObj(SWIG_as_voidptr(err),
 				    SWIGTYPE_p_nlmsgerr, 0 |  0 );
-	cbparobj = Py_BuildValue("(OO)", errobj, cbd->cba);
-	resobj = PyObject_CallObject(cbd->cbf, cbparobj);
+	/* add selfobj if callback is a method */
+	if (cbd->cbf && PyMethod_Check(cbd->cbf)) {
+		PyObject *selfobj = PyMethod_Self(cbd->cbf);
+		cbparobj = Py_BuildValue("(OOO)", selfobj ? selfobj : cbd->cba,
+					 errobj, cbd->cba);
+		funcobj = PyMethod_Function(cbd->cbf);
+	} else {
+		cbparobj = Py_BuildValue("(OO)", errobj, cbd->cba);
+		funcobj = cbd->cbf;
+	}
+	resobj = PyObject_CallObject(funcobj, cbparobj);
 	Py_DECREF(cbparobj);
 	if (resobj == NULL)
 		return NL_STOP;
-- 
1.7.10.4