Re: proposal: simplify prologue alternatives into %code

[Paolo Bonzini]

Hans Aberg wrote:
> On 4 Jan 2007, at 06:56, Joel E. Denny wrote:
>
> > 5. Hans suggested we drop the quotes around "QUALIFIER" or "NAME".  I
> > think that idea may have some merit, but lets debate this detail only
> > after resolving the larger issues here.
>
> I agree in that. Though important to get a nice syntax, getting the 
> other stuff together is more important. :-)
>
> In order to get the C++ class polymorphy working with the Bison static 
> type system, would need an additional feature, and I am not sure exactly 
> how it relates to %define and %code, though some additional macro is 
> needed:

You can set up the skeleton like this:

%define "cast" "dynamic_cast"
%define "cast" "static_cast"
%define "cast" "" (or default) -> union

...

> In the C++ class polymorphy variations, I had to write something like
>   dynamic_cast<type>(*$k.data())
>   static_cast<type>(*$k.data())

... if you are ok with

dynamic_cast<type>(*$k)

that is, instead of

struct container {
  top_class *member;
  top_class *data () { return member; }
}

you have to write this:

struct container {
  top_class *member;
  top_class &operator *() { return *member; }
}

Paolo