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

[Jeff Franks <jcf tpg com au>]

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.

Regards,
Jeff Franks.