From: David Klein (dave_chp_at_[hidden])
Date: 2006-09-29 11:07:05
scott velasquez wrote:
> Here is what I desire to have in my GUI library as it pertains to boost:
>
> 1. No raw widgt pointers. Container functions should take a reference to a
> base class smart pointer type rather then accepting raw pointers of the base
> class type.
> 2. Containers store an array of smart pointers of the base GUI widget type.
> This is needed because containers can contain many widget derived types.
>
> I'm just showing the class code that matters; Normally, you would have
> constructors, destructors, access label, etc.
>
> class OWidget;
>
> class ODerivedWidget : public OWidget;
>
> class OWidgetContainer : public OWidget
> {
> public:
>
> void Add( boost::shared_ptr<OWidget>& widget )
> {
> mWidgets.pushback(widget);
> }
>
> std::vector<boost::shared_ptr<OWidget>> mWidgets;
> }
>
> int main(void)
> {
> OWidgetContainer root;
>
> // Works just fine since the types match
> boost::shared_ptr<OWidget> base(new OWidget());
> root.Add(base);
>
> // Doesn't work since the Add() function can't convert ODerivedWidget
> shared pointer to OWidget shared pointer type.
> boost::shared_ptr<ODerivedWidget> derived(new ODerivedWidget());
> root.Add( derived);
> }
>
> Is this even possible? I've read about boost::any and boost:variant and
> while that might solve my problem of storing smart pointers of differing
> types, it doesn't allow me to pass smart pointers of derived types.
>
> Any ideas/suggestions would be GREATLY appreciated!
>
> -scottv
>
>
hi scott,
make your Add() function take const references and it works.
void Add( const boost::shared_ptr<OWidget>& widget )
-- HTH dave