Re: [sigc] current work on libsigc2

[Martin Schulze <martin-ml hippogriff de>]

Am 2003.09.03 18:29 schrieb(en) Murray Cumming:
> I think you forgot to add reference_wrapper.h to cvs.

Yes, thanks for notifying me.

> All the recent ChangeLog stuff looks very impressive but mostly
> incomprehensible to me. I'll try to get familiar with the code again.
>
> I'm surprised that you could do without typeof, but I don't know the
> details. Is the boost thing using typeof?

No, boost is not using typeof(). typeof() seems to be supported by gcc
only (and has a bug with references there).

The details in short are that we have to make the assumption that
functors define "typedef ... result_type;". If you use 3rd-party
functors in libsigc++2 there are two policies:
- writing "namespace sigc { namespace functor {
                                 SIGC_FUNCTORS_HAVE_RESULT_TYPE } }"
  in your source means that all 3rd-party functors you use define
  "typedef ... result_type".
- writing "namespace sigc { namespace functor {
        SIGC_FUNTOR_TRAIT(your_functor, the_result_type) } }"
  specifies the result type of functor "your_functor".
Multi-type functors can only be supported through typeof().

Adaptors have a more complicated logic for return type deduction,
especially to support lambdas, but eventually it all comes down
to the principle described above.

> Once again, please release early, release often. Don't wait for
> decisions or fixes before releasing. If you don't then I will.

Okay, I will release a new version tomorrow. I have some work
on lambda operators pending that I will finish now.

Regards,

  Martin