Re: [Boost-users] Yet another boost::enable_shared_from_this question

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-05-26 11:36:10

Yaoltzin Gomez wrote:

> Basically, what I have is this:
>
> class Base : public boost::enable_shared_from_this<Base>
> {
>    boost::shared_ptr<Base> GetBasePointer()
>    {
>       return shared_from_this();
>    }
>
>    void Foo()
>    {
>       shared_ptr<Child> child( new Child );
>       AddChild( child, GetBasePointer() );
>    }
> };
>
> class Derived: public Base, public
> boost::enable_shared_from_this<Derived> {
>    boost::shared_ptr<Derived> GetDerivedPointer()
>    {
>       return shared_from_this();
>    }

[...]

One way to avoid putting more than one enable_shared_from_this<> base into 
Derived is to use

class Derived: public Base
{
    boost::shared_ptr<Derived> GetDerivedPointer()
    {
       return dynamic_pointer_cast<Derived>( shared_from_this() );
    }

    // ...
};

static_pointer_cast will also work in this case (it will fail if Derived 
uses virtual inheritance).