Re: [sigc] current work on libsigc2

[Murray Cumming <murrayc usa net>]

On Wed, 2003-09-03 at 21:31, Martin Schulze wrote:
> 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).

That's good then. Well done.

> 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().

And does boost have a similar system, or limitation? I'd probably need
an example, to understand what a "3rd party functor" really is, or how I
might use it. I suspect it's not a big deal.

> 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.

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

Great.

-- 
Murray Cumming
murrayc usa net
www.murrayc.com