Re: [Boost-users] Bind signals together

From: Will (whenderson_at_[hidden])
Date: 2006-01-09 19:02:28

Aha. boost::ref is exactly what I needed. Thank you so much for your consise
and informative reply!

"Peter Dimov" <pdimov_at_[hidden]> wrote in message
news:007701c61515$20de1680$6407a8c0_at_pdimov2...
> Will wrote:
> > Hi, I'm looking for a general technique for binding signals with
> > varying signatures together.
> > Obviously i can create custom functions for any specific case, but i'm
> > wondering if boost::bind could be used to help out here?
> >
> > i.e.
> >
> > boost::signal1<void, const char *> sig1;
> > boost::signal0<void> sig2;
> >
> > void bing() {
> >  std::cout << "bing" << std::endl;
> > }
> >
> > // connect sig1 to sig2 such that calling sig1 will invoke sig2
> > // ... <- how do i do this?
> >
> > // connect sig2 to some function
> > sig2.connect(&bing);
>
>     sig1.connect( boost::bind( boost::ref( sig2 ) ) );
>
> should work. In general, boost::bind( f, a1, a2... ) will call f( a1,
> a2... ), so bind( f ) will simply call f(); the argument will be ignored
> (because there is no _1 in the bound argument list).
>
> Another (clearer) example of bind ignoring an input argument is bind( f,
> _2 ), which only passes the second argument and ignores the first.
>
> The ref() is needed since sig2 is noncopyable.
>
> > // call the signal
> > sig1("some string");