[pygtk] Diiference between method and a function

[John Dennis]

On Thu, 2007-06-14 at 02:42 -0700, varun_shrivastava wrote:
> hi
> 
> i was reading about how to define a wrapper function
> it looks like 
> 
> static PyObject *
> spam_system(PyObject *self, PyObject *args)
> {
>     const char *command;
>     int sts;
> 
>     if (!PyArg_ParseTuple(args, "s", &command))
>         return NULL;
>     sts = system(command);
>     return Py_BuildValue("i", sts);
> }
> 
> and then i couldn't understand this line
> 
> "The self argument is only used when the C function implements a built-in
> method, not a function. In the example, self will always be a NULL pointer,
> since we are defining a function, not a method."
> 
> what is built in method ?

The term built-in is I suspect erroneous in this instance. In python
speak built-in refers to something you do not have to load via an
import, I suspect Guido's language may have been a little sloppy when he
really meant a function or method implemented in C using the CPython
API.

What the Guido (the author) is trying to elucidate is the distinction
between a function and a method. Methods are attributes of a class
object and are bound to a class instance via self. Functions don't exist
within a class, thus they do not have an object to bind to via the self
parameter. Always passing self is a simplification in CPython so one
does not need two interfaces.
-- 
John Dennis <jdennis at redhat.com>