[boost] Re: 'function' idea

From: Dirk Gerrits (dirk_at_[hidden])
Date: 2002-11-09 09:45:19

Aleksey Gurtovoy wrote:

> Dirk Gerrits wrote:
>
> >I still don't get it. Have I used to few widget libraries? ;)
>
>
> OK, we are drifting from the actual topic here, but I really don't 
> like the
> fact that I can't express myself clearly tonight :). So, here we go:
>
>     class widget_model
>     {
>      public:
>         // ...
>         typedef boost::function bool_arg_t;
>
>         self_t&     is_enabled(bool_arg_t a_enabled)
>         {
>             is_enabled_ = a_enabled;
>             return *this;
>         }
>
>         bool        is_enabled() const
>         {
>             return is_enabled_();
>         }
>
>      private:
>         bool_arg_t  is_enabled_;
>     };
>
>
>     class win32_widget_impl
>     {
>      public:
>         win32_widget_impl( /* ... */)
>         {
>             // setup this->on_idle() to be called, well, on idle
>         }
>
>         void on_idle()
>         {
>             // sync itself with the model
>             ::EnableWindow(hwnd_, model_->is_enabled());
>         }
>
>      private:
>         HWND hwnd_;
>         ref_ptr model_;
>     };
>
> Since the model is passive here, everything works as per my first example
> (given 'widget' -> 'widget_model' substitution).

Ahh, now I understand. Looks cool indeed. However I'm not sure how often 
this might be useful. Perhaps smarter people than I can think of more 
examples?

Dirk