Re: [sigc] How to use sigc::bind<>

[rsteinke w-link net]

> From: Murray Cumming Comneon com
>
> > [mailto:libsigc-list-admin gnome org] On Behalf Of Jeff Franks
> > Martin Schulze wrote:
> > 
> > >   void bar(int,int);
> > >   some_signal.connect(sigc::bind<0>(&bar,10,20));
> > >     // binds two arguments at a time
> > >
> > >   sigc::signal<void,int> other_signal;
> > >   other_signal.connect(sigc::bind<0>(&bar,20));
> > >     // binds to the last (second) argument of bar
> > >   other_signal.connect(sigc::bind<1>(&bar,10));
> > >     // binds to the first argument of bar
> > >
> > This is where I had confusion, bind<0> binds to the last 
> > argument, not 
> > the first, as zero might imply. I find the explanation bind<0> (zero) 
> > binds to the last (second) argument of bar confusing. Compared with 
> > bind<1> (first) binds to the first argument of bar, which sounds 
> > logical. Initially I thought that the # in bind<#> meant that 
> > you could 
> > specify which argument position in the bound function the 
> > bound argument 
> > would be passed to, such as zero for the first, 1 for the 
> > second, 2 for 
> > the third, etc, like a zero-based index. That would leave bind<#> to 
> > create a slot functor with one less argument, based on the remaining 
> > arguments, as is required.
> > 
> > I'm sure this will confuse many programmers.
>
> It confuses me.

Perhaps negative numbers could be used to indicate arguments at
the end of the slot (i.e., -1 for the last argument, -2 for the next-to-last,
etc.)?

Ron Steinke