mirror of https://github.com/python/cpython
Redo the PyMethod attributes using a dir()-friendly approach, creating
descriptors for each attribute. The getattr() implementation is similar to PyObject_GenericGetAttr(), but delegates to im_self instead of looking in __dict__; I couldn't do this as a wrapper around PyObject_GenericGetAttr(). XXX A problem here is that this is a case of *delegation*. dir() doesn't see exactly the same attributes that are actually defined; e.g. if the delegate is a Python function object, it supports attributes like func_code etc., but these are not visible to dir(); on the other hand, dynamic function attributes (stored in the function's __dict__) *are* visible to dir(). Maybe we need a mechanism to tell dir() about the delegation mechanism? I vaguely recall seeing a request in the newsgroup for a more formal definition of attribute delegation too. Sigh, time for a new PEP.
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@ -2000,58 +2000,90 @@ PyMethod_New(PyObject *func, PyObject *self, PyObject *class)
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return (PyObject *)im;
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}
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/* Class method methods */
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/* Descriptors for PyMethod attributes */
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/* im_class, im_func and im_self are stored in the PyMethod object */
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#define OFF(x) offsetof(PyMethodObject, x)
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static struct memberlist instancemethod_memberlist[] = {
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{"im_func", T_OBJECT, OFF(im_func)},
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{"im_self", T_OBJECT, OFF(im_self)},
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{"im_class", T_OBJECT, OFF(im_class)},
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/* Dummies that are not handled by getattr() except for __members__ */
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{"__doc__", T_INT, 0},
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{"__name__", T_INT, 0},
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{"__dict__", T_OBJECT, 0},
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{"im_class", T_OBJECT, OFF(im_class), READONLY|RESTRICTED},
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{"im_func", T_OBJECT, OFF(im_func), READONLY|RESTRICTED},
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{"im_self", T_OBJECT, OFF(im_self), READONLY|RESTRICTED},
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{NULL} /* Sentinel */
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};
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static int
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instancemethod_setattro(register PyMethodObject *im, PyObject *name,
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PyObject *v)
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{
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char *sname = PyString_AsString(name);
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PyErr_Format(PyExc_TypeError, "read-only attribute: %s", sname);
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return -1;
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}
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/* __dict__, __doc__ and __name__ are retrieved from im_func */
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static PyObject *
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instancemethod_getattro(register PyMethodObject *im, PyObject *name)
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im_get_dict(PyMethodObject *im)
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{
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PyObject *rtn;
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char *sname = PyString_AsString(name);
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if (sname[0] == '_') {
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/* Inherit __name__ and __doc__ from the callable object
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implementing the method */
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if (strcmp(sname, "__name__") == 0 ||
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strcmp(sname, "__doc__") == 0)
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return PyObject_GetAttr(im->im_func, name);
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}
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if (PyEval_GetRestricted()) {
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PyErr_SetString(PyExc_RuntimeError,
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"instance-method attributes not accessible in restricted mode");
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return NULL;
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}
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if (sname[0] == '_' && strcmp(sname, "__dict__") == 0)
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return PyObject_GetAttr(im->im_func, name);
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return PyObject_GetAttrString(im->im_func, "__dict__");
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}
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rtn = PyMember_Get((char *)im, instancemethod_memberlist, sname);
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if (rtn == NULL && PyErr_ExceptionMatches(PyExc_AttributeError)) {
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PyErr_Clear();
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rtn = PyObject_GetAttr(im->im_func, name);
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static PyObject *
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im_get_doc(PyMethodObject *im)
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{
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return PyObject_GetAttrString(im->im_func, "__doc__");
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}
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static PyObject *
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im_get_name(PyMethodObject *im)
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{
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return PyObject_GetAttrString(im->im_func, "__name__");
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}
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static struct getsetlist instancemethod_getsetlist[] = {
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{"__dict__", (getter)im_get_dict},
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{"__doc__", (getter)im_get_doc},
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{"__name__", (getter)im_get_name},
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{NULL} /* Sentinel */
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};
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/* The getattr() implementation for PyMethod objects is similar to
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PyObject_GenericGetAttr(), but instead of looking in __dict__ it
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asks im_self for the attribute. Then the error handling is a bit
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different because we want to preserve the exception raised by the
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delegate, unless we have an alternative from our class. */
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static PyObject *
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instancemethod_getattro(PyObject *obj, PyObject *name)
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{
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PyMethodObject *im = (PyMethodObject *)obj;
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PyTypeObject *tp = obj->ob_type;
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PyObject *descr, *res;
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descrgetfunc f;
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if (tp->tp_dict == NULL) {
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if (PyType_Ready(tp) < 0)
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return NULL;
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}
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return rtn;
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descr = _PyType_Lookup(tp, name);
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f = NULL;
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if (descr != NULL) {
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f = descr->ob_type->tp_descr_get;
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if (f != NULL && PyDescr_IsData(descr))
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return f(descr, obj, (PyObject *)obj->ob_type);
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}
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res = PyObject_GetAttr(im->im_func, name);
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if (res != NULL || !PyErr_ExceptionMatches(PyExc_AttributeError))
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return res;
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if (f != NULL) {
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PyErr_Clear();
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return f(descr, obj, (PyObject *)obj->ob_type);
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}
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if (descr != NULL) {
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PyErr_Clear();
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Py_INCREF(descr);
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return descr;
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}
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assert(PyErr_Occurred());
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return NULL;
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}
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static void
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@ -2298,7 +2330,7 @@ PyTypeObject PyMethod_Type = {
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instancemethod_call, /* tp_call */
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0, /* tp_str */
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(getattrofunc)instancemethod_getattro, /* tp_getattro */
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(setattrofunc)instancemethod_setattro, /* tp_setattro */
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PyObject_GenericSetAttr, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
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0, /* tp_doc */
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@ -2309,8 +2341,8 @@ PyTypeObject PyMethod_Type = {
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0, /* tp_iter */
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0, /* tp_iternext */
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0, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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instancemethod_memberlist, /* tp_members */
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instancemethod_getsetlist, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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instancemethod_descr_get, /* tp_descr_get */
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