Re: [PATCH v2] Allow calling of user-defined function call operators

[Hannes Domani <ssbssa@yahoo.de>]

 Am Freitag, 3. Mai 2024 um 22:06:46 MESZ hat Tom Tromey <tom@tromey.com> Folgendes geschrieben:

> >>>>> "Hannes" == Hannes Domani <ssbssa@yahoo.de> writes:
>
> Hannes> The change in operation::evaluate_funcall is to make sure the type
> Hannes> fields are only used for function types, only they use them as the
> Hannes> argument types.
>
> IIRC the evaluation operations are all kind of complicated and
> hairy... but it seems to me that the type of the chosen overload of
> operator() would supply the type here?

Here the overload of operator() is chosen based on the argument values,
not the other way round.


> Hannes> +  type *ftype = callee->type ();
> Hannes> +
> Hannes> +  /* If the callee is a struct, there might be a user-defined function call
> Hannes> +    operator that should be used instead.  */
> Hannes> +  std::vector<value *> vals;
> Hannes> +  if (overload_resolution
> Hannes> +      && exp->language_defn->la_language == language_cplus
> Hannes> +      && check_typedef (ftype)->code () == TYPE_CODE_STRUCT)
> Hannes> +    {
>
> One question to consider is whether this should be done in the
> expression node or elsewhere.  Other operator overloads are handled in
> the value API instead.
>
> I'm not sure which is better.  It would probably be cleaner to do it in
> the expression nodes, like you've done.  Actually the best would
> probably be to make a new operation subclass and avoid the need for a
> language check.

I've now moved the logic into evaluate_subexp_do_call so all operation
subclasses would profit from this, so I don't understand how a new
operation subclass would work for this.


> However, the value API is convenient to use -- for example, this is what
> makes operator overloading work in the Python API.
>
> You can see the distinction with this patch by trying to call a
> struct-with-operator() object from Python.

Calling a struct-with-operator() object from Python does not work, because
valpy_call directly calls call_function_by_hand.
It would maybe be possible to also call evaluate_subexp_do_call there.


Hannes