Argument Clinic no longer works with single optional argument #68239

Activity

1. serhiy-storchaka commented on Apr 24, 2015

   

   serhiy-storchaka

   on Apr 24, 2015

   MemberAuthor

   More actions

   Argument Clinic no longer works single optional argument. For example see _tkinter.tkapp.wantobjects in the patch in bpo-20168.

   /*[clinic input]
   _tkinter.tkapp.wantobjects

   [
   value: int
   ]
   /
   

   [clinic start generated code]*/

   It is converted to the methoddef of type METH_O.

   #define _TKINTER_TKAPP_WANTOBJECTS_METHODDEF    \
       {"wantobjects", (PyCFunction)_tkinter_tkapp_wantobjects, METH_O, _tkinter_tkapp_wantobjects__doc__},
   
   static PyObject *
   _tkinter_tkapp_wantobjects(PyObject *self, PyObject *arg)
   {
       PyObject *return_value = NULL;
       int group_right_1 = 0;
       int value = 0;

       if (!PyArg_Parse(arg, "i:wantobjects", &value))
           goto exit;
       return_value = _tkinter_tkapp_wantobjects_impl(self, group_right_1, value);

   exit:
       return return_value;
   }

   As result wantobjects() can't be called without an argument.
2. serhiy-storchaka

   added

   topic-argument-clinic

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Apr 24, 2015
3. larryhastings commented on May 3, 2015

   

   larryhastings

   on May 3, 2015

   Contributor

   More actions

   Optional groups were designed to support two specific legacy use cases:

   • functions that have groups of parameters that are
   • functions with optional parameters to the left of required parameters

   They are not intended to be used in cases like this. I really, really wish you would stop using them except for these specific legacy cases.

   Furthermore, the argument parsing for tkinter.tkapp.wantobjects has a very clear translation into Argument Clinic:

   value: int = -1
   /
   

   Optional groups should not be used for single-argument functions. I have no interest in fixing this bug.
4. larryhastings commented on May 3, 2015

   

   larryhastings

   on May 3, 2015

   Contributor

   More actions

   Sorry, I forgot to finish the first bullet point. It should have read:

   • functions that have groups of parameters that are optional only as a group (e.g. curses.window.getch)
5. serhiy-storchaka commented on May 3, 2015

   

   serhiy-storchaka

   on May 3, 2015

   MemberAuthor

   More actions

   Then it would be better to not convert wantobjects() to Argument Clinic. Using -1 as a value for not passed argument is a hack (added in 1ab9978123be) and I don't want to propagate it to the signature.

   But I afraid that there are other functions that suffer from this bug (may be in the curses module).
6. serhiy-storchaka

   added

   staleStale PR or inactive for long period of time.Stale PR or inactive for long period of time.

   on May 3, 2015
7. larryhastings commented on May 3, 2015

   

   larryhastings

   on May 3, 2015

   Contributor

   More actions

   If the argument currently uses a default value of -1, then I see no problem with converting it to Argument Clinic using a default value of -1. If you claim it's a "hack" then you should discuss that with the author of 1ab9978123be.
8. larryhastings commented on May 3, 2015

   

   larryhastings

   on May 3, 2015

   Contributor

   More actions

   Closing as wontfix. This is not a supported use of optional groups.
9. larryhastings

   closed this as completedon May 3, 2015
10. larryhastings

    removed

    staleStale PR or inactive for long period of time.Stale PR or inactive for long period of time.

    on May 3, 2015
11. ezio-melotti

    transferred this issue fromon Apr 10, 2022