Hi,
I have some questions about signals.
If I add a function to both Hello and World, from the "Hello World"
example, called alternate() and set up signals like so:
boost::signal sig_h;
boost::signal< void (World*) > sig_w;
sig_h.connect(boost::mem_fn(&Hello::alternate));
sig_w.connect(boost::mem_fn(&World::alternate));
I have to define two different signals since the object type is part of
the signal definition. Is there an easy way to get a single signal to
call the alternate() function of both Hello and World?
I recently found this signal slot solution.
http://www.codeproject.com/cpp/ElmueSignalsandSlots.asp
There is an extra level of indirection here, in that you define a slot
that points to the function. I'd be interested to see what people on
this forum think about this solution. If I understand things correctly,
this solution doesn't seem to fit into the categories listed in the
"Choice of Slot Definitions" docs.
Also a general signal slot question. What are the main reasons why
developers don't use an inherited pure interface for every callback
type? A signal would be a template class with a list of pointers to the
interface and some methods to operate on the list. Not flexible enough?
Doesn't scale well to larger uses? Time spent calling virtual
functions? I saw this in the boost signal docs that might apply - "the
use of a large number of small adaptor classes containing virtual
functions has been found to cause an unacceptable increase in the size
of executables (polymorphic class types require more code than
non-polymorphic types)".
Thanks
Frank
