Dear Robert, thank you very much for your answer. I understand what you mean and I have looked at slice object and C-api methods it provides. It should be easy to implement it.
The only question is how exactly yo implement the general getter, since sq_item you mention (assume you mean PySequenceMethods.sq_item) has the following signature: PyObject * (* ssizeargfunc)(PyObject *, Py_ssize_t) accepting Py_ssize_t as the index, not a PyObject * which would hold the slice. So, how exactly to implement the getter? As a general method named __getitem__ registered in PyMethodDef? Or in another way? Thank you very much again. Regards, Dan ----- PŮVODNÍ ZPRÁVA ----- Od: "Robert Kern" <robert.k...@gmail.com> Komu: python-list@python.org Předmět: Re: Slices when extending python with C++ Datum: 28.12.2011 - 10:24:42 > On 12/27/11 11:02 PM, roze...@volny.cz wrote: > > Hallo, > > I have kind of special question when extening > > python with C++ > > > implemented modules. > > > > I try to implement a class, behaving also like > > an array. And I need > > > to implement slice-getters. I implemented > > PySequenceMethods.sq_slice > > > to get "simple" slices like: > > > > myobj[x:y] > > > > It works perfectly, without problems. But now I > > have a problem when > > > need to access the array with "special" slices, > > like: > > > > > myobj[x:y:step] > > myobj[::-1] # to revert the array > > > > I would like to ask which method must be > > implemented to get this > > > "special" slice getters. The "simple" slice > > PySequenceMethods.sq_slice getter accepts only > > two indexes - from, > > > to, but not a step (which would solve the > > issue). > > > The sq_slice slot is deprecated, just like the > __getslice__() method on the > Python side. Instead, implement sq_item to accept > a slice object in addition to > integer indices. > > http://docs.python.org/c-api/slice.html > > -- > Robert Kern > > "I have come to believe that the whole world is an > enigma, a harmless enigma > that is made terrible by our own mad attempt to > interpret it as though it had > an underlying truth." > -- Umberto Eco > > -- > http://mail.python.org/mailman/listinfo/python-list > -- Tradiční i moderní adventní a novoroční zvyky, sváteční jídlo a pití, výzdoba a dárky... - čtěte vánoční a silvestrovský speciál portálu VOLNÝ.cz na http://web.volny.cz/data/click.php?id=1301 -- http://mail.python.org/mailman/listinfo/python-list
