Dirk Gerrits wrote:
> > So, the corrected example would be:
> >
> > class widget
> > {
> > public:
> > // ...
> > typedef boost::function bool_arg_t;
> >
> > self_t& is_enabled(bool_arg_t a_enabled); // note the
> > signature!
> > bool is_enabled() const;
> > };
> >
> > int main()
> > {
> > widget w;
> > w.is_enabled(true); // ordinary syntax/semantics
> > assert(w.is_enabled())
> >
> > widget w2;
> > w.is_enabled(boost::bind(&widget::is_enabled,
> &w2)); // here!
> > w2.is_enabled(false);
> > assert(!w.is_enabled()) // !
> > }
> >
> > I hope the name change makes the semantics of the above clearer.
>
> 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 ()> 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<widget_model,!0> model_;
};
Since the model is passive here, everything works as per my first example
(given 'widget' -> 'widget_model' substitution).
Aleksey
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