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

[Michael Mercier <michael.mercier-MZpvjPyXg2s@public.gmane.org>]

Hi Jean,

I just tried you patch and I got an error when I try to import the 
smbus python package:

import smbus

ImportError: 
/usr/local/lib/python3.2/dist-packages/smbus.cpython-32mu.so: undefined 
symbol: i2c_smbus_process_call

Any idea?

Thanks,

Michael Mercier

Le lun. 19 janv. 2015 à 23:03, Jean Delvare <jdelvare-l3A5Bk7waGM@public.gmane.org> a 
écrit :
> 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