On Thu, May 5, 2011 at 3:38 AM, Amaury Forgeot d'Arc <amaur...@gmail.com> wrote: > Hi, > > Le jeudi 5 mai 2011, Greg Ewing <greg.ew...@canterbury.ac.nz> a écrit : >> Amaury Forgeot d'Arc wrote: >> >> >> It's in the file Doc/data/refcounts.dat >> in some custom format. >> >> >> However, it doesn't seem to quite convey the same information. >> It lists the "refcount effect" on each parameter, but translating >> that into the notion of borrowed or stolen references seems >> to require knowledge of what the function does. >> >> For example, PyDict_SetItem has: >> >> PyDict_SetItem:PyObject*:p:0: >> PyDict_SetItem:PyObject*:key:+1: >> PyDict_SetItem:PyObject*:val:+1: >> >> All of these parameters take borrowed references, but the >> key and val get incremented because they're being stored >> in the dict. > > This is not always true, for example when the item is already present > in the dict. > It's not important to know what the function does to the object, > Only the action on the reference is relevant. > >> >> So this file appears to be of limited usefulness.
Seems you're in agreement with this. IMO when references are borrowed it is not very interesting. The interesting thing is when calling a function *steals* a reference. The other important thing to know is whether the caller ends up owning the return value (if it is an object) or not. I *think* you can tell the latter from the +1 for the return value; but the former (whether it steals a reference) is unclear from the data given. There's even an XXX comment about this in the file: # XXX NOTE: the 0/+1/-1 refcount information for arguments is # confusing! Much more useful would be to indicate whether the # function "steals" a reference to the argument or not. Take for # example PyList_SetItem(list, i, item). This lists as a 0 change for # both the list and the item arguments. However, in fact it steals a # reference to the item argument! -- --Guido van Rossum (python.org/~guido) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
