Re: i2c-tools: add compatibility for python2/3 to py-smbus

[Jean Delvare <jdelvare-l3A5Bk7waGM@public.gmane.org>]

Hi Angelo,

On Mon, 19 Jan 2015 16:13:26 +0100, Angelo Compagnucci wrote:
> Dear Jean Delvare,
> 
> Attached you can find a patch that implements py-smbus for python3
> with python2 backward compatibility.
> This patch is not heavily tested, but it wors well for me.

Thanks a lot for your work. I was finally about to look into this and
you saved me some time :-)

> Unfortunately, I don't know how to use svn for sharing source code, it
> is so ugly compared to git and it doesn't provide a way to send
> patches via email, so the best way I found was to attach the patch
> file.

This is fine. You know, this is how people did before git was invented,
and it worked well ;-)

> Hope this helps!

Oh yeah. I started from your version and improved it as follows:
* Added back missing header files as pointed out by Michael. I have a
  hard time believing you did not need these.
* Reverted some undesirable white space changes.
* Turned most #ifndefs into #ifdefs for readability.
* Shared the module documentation string.
* Added some preprocessing magic to limit the number of #ifdefs.
* Dropped PY3 definition.

Result is below, my patch is significantly smaller and the resulting
code is IMHO more readable. It builds fine for both python 2.7 and 3.3,
however I can't test it, so I would appreciate if you guys could test
and report. If it works fine I'll commit it tomorrow.

For convenience I have also put the pre-patched file at:
http://jdelvare.nerim.net/devel/i2c-tools/smbusmodule.c

Thanks.
---
 py-smbus/smbusmodule.c |   47 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 45 insertions(+), 2 deletions(-)

--- i2c-tools.orig/py-smbus/smbusmodule.c	2015-01-19 22:09:39.624016377 +0100
+++ i2c-tools/py-smbus/smbusmodule.c	2015-01-19 22:59:03.651572099 +0100
@@ -94,7 +94,11 @@ SMBus_dealloc(SMBus *self)
 	PyObject *ref = SMBus_close(self);
 	Py_XDECREF(ref);
 
+#if PY_MAJOR_VERSION >= 3
+	Py_TYPE(self)->tp_free((PyObject *)self);
+#else
 	self->ob_type->tp_free((PyObject *)self);
+#endif
 }
 
 #define MAXPATH 16
@@ -434,11 +438,19 @@ SMBus_list_to_data(PyObject *list, union
 
 	for (ii = 0; ii < len; ii++) {
 		PyObject *val = PyList_GET_ITEM(list, ii);
+#if PY_MAJOR_VERSION >= 3
+		if (!PyLong_Check(val)) {
+			PyErr_SetString(PyExc_TypeError, msg);
+			return 0; /* fail */
+		}
+		data->block[ii+1] = (__u8)PyLong_AS_LONG(val);
+#else
 		if (!PyInt_Check(val)) {
 			PyErr_SetString(PyExc_TypeError, msg);
 			return 0; /* fail */
 		}
 		data->block[ii+1] = (__u8)PyInt_AS_LONG(val);
+#endif
 	}
 
 	return 1; /* success */
@@ -637,9 +649,14 @@ static PyGetSetDef SMBus_getset[] = {
 };
 
 static PyTypeObject SMBus_type = {
+#if PY_MAJOR_VERSION >= 3
+	PyVarObject_HEAD_INIT(NULL, 0)
+	"SMBus",			/* tp_name */
+#else
 	PyObject_HEAD_INIT(NULL)
 	0,				/* ob_size */
 	"smbus.SMBus",			/* tp_name */
+#endif
 	sizeof(SMBus),			/* tp_basicsize */
 	0,				/* tp_itemsize */
 	(destructor)SMBus_dealloc,	/* tp_dealloc */
@@ -678,24 +695,50 @@ static PyTypeObject SMBus_type = {
 	SMBus_new,			/* tp_new */
 };
 
+#if PY_MAJOR_VERSION >= 3
+static struct PyModuleDef SMBusModule = {
+	PyModuleDef_HEAD_INIT,
+	"SMBus",			/* m_name */
+	SMBus_module_doc,  		/* m_doc */
+	-1,				/* m_size */
+	NULL,				/* m_methods */
+	NULL,				/* m_reload */
+	NULL,				/* m_traverse */
+	NULL,				/* m_clear */
+	NULL,				/* m_free */
+};
+#define INIT_RETURN(m)	return m
+#define INIT_FNAME	PyInit_smbus
+#else
 static PyMethodDef SMBus_module_methods[] = {
 	{NULL}
 };
+#define INIT_RETURN(m)	return
+#define INIT_FNAME	initsmbus
+#endif
 
 #ifndef PyMODINIT_FUNC	/* declarations for DLL import/export */
 #define PyMODINIT_FUNC void
 #endif
 PyMODINIT_FUNC
-initsmbus(void) 
+INIT_FNAME(void)
 {
 	PyObject* m;
 
 	if (PyType_Ready(&SMBus_type) < 0)
-		return;
+		INIT_RETURN(NULL);
 
+#if PY_MAJOR_VERSION >= 3
+	m = PyModule_Create(&SMBusModule);
+#else
 	m = Py_InitModule3("smbus", SMBus_module_methods, SMBus_module_doc);
+#endif
+	if (m == NULL)
+		INIT_RETURN(NULL);
 
 	Py_INCREF(&SMBus_type);
 	PyModule_AddObject(m, "SMBus", (PyObject *)&SMBus_type);
+
+	INIT_RETURN(m);
 }
 

-- 
Jean Delvare
SUSE L3 Support