On Nov 27, 2007 2:16 AM, Nick Coghlan <[EMAIL PROTECTED]> wrote:
> Greg Ewing wrote:
> > Guido van Rossum wrote:
> >> They have that too. See:
> >>
> >>>>> f = list.append
> >>>>> g = f.__get__(a)
> >>>>> g
> >> <built-in method append of list object at 0x590f8>
> >
> > Hmmm. It seems that C method objects are more
> > like an unbound method object that's pre-bound to a
> > particular class.
> >
> > I'm concerned with built-in function objects that
> > are *not* methods of anything. I'm suggesting they
> > should behave the same way as a Python function when
> > you put one in a class, i.e. accessing it through an
> > instance creates a bound method.
>
> I think I see what you're getting at now - adding a '__get__' method to
> the basic C function wrapper that returns self when retrieved from the
> class, and a bound instancemethod when retrieved from an instance.
>
> To illustrate the difference between builtin functions and methods:
>
> >>> type(str.lower)
> <type 'method_descriptor'>
> >>> '__get__' in dir(str.lower)
> True
>
> >>> type(map)
> <type 'builtin_function_or_method'>
> >>> '__get__' in dir(map)
> False
>
> This seems like an eminently sensible idea to me, and not really
> something that can be done in the 2.x series.
On second thought (after responding to Greg), I agree that it is
sensible. But why can't it be done in 2.6?
The attached implementation is simple enough...
--
--Guido van Rossum (home page: http://www.python.org/~guido/)
Index: Objects/methodobject.c
===================================================================
--- Objects/methodobject.c (revision 59193)
+++ Objects/methodobject.c (working copy)
@@ -157,6 +157,19 @@
return self;
}
+static PyObject *
+meth_descr_get(PyObject *m, PyObject *obj, PyObject *type)
+{
+ if (((PyCFunctionObject *)m)->m_self != NULL ||
+ obj == NULL || obj == Py_None)
+ {
+ Py_INCREF(m);
+ return m;
+ }
+ return PyMethod_New(m, obj);
+}
+
+
static PyGetSetDef meth_getsets [] = {
{"__doc__", (getter)meth_get__doc__, NULL, NULL},
{"__name__", (getter)meth_get__name__, NULL, NULL},
@@ -264,6 +277,8 @@
meth_getsets, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
+ meth_descr_get, /* tp_descr_get */
+ 0, /* tp_descr_set */
};
/* Find a method in a method chain */
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