Re: [boost] shared_ptr question

From: H (h.v.niekerk_at_[hidden])
Date: 2005-06-22 00:45:01

> Let's see if I can recast your problem to something a little
> simpler to discuss:
> 
>    void function2(some_type data) // stores stuff in caller's object
>    {
>       read_something_from_somewhere(data);
>    }
> 
>    void function1(some_type data) // stores stuff in caller's object
>    {
>       function2(data);
>    }
> 
>    void function3(some_type data)
>    {
>       // do something useful with data
>    }
> 
>    int main()
>    {
>       some_type data; // some pointer type
>       function1(data); // stores stuff in data
>       function3(data);
>    }
> 
> Is that a good approximation of what you want?

Yes, that looks like it.

> 
> If so, some_type should be boost::shared_ptr<something> and the
> rest should just work.  Of course, you can avoid using
> boost::shared_ptr if function1() and function2() take non-const
> references to some_type:
> 
>    void function2(some_type & data) // stores stuff in caller's object
>    {
>       read_something_from_somewhere(data);
>    }
> 
>    void function1(some_type & data) // stores stuff in caller's object
>    {
>       function2(data);
>    }
> 
>    void function3(some_type const & data)
>    {
>       // do something useful with data
>    }
> 
>    int main()
>    {
>       some_type data; // not a pointer type
>       function1(data); // stores stuff in data
>       function3(data);
>    }
> 
OK. The original way was:

auto_ptr<FtInterface> fti (ftGetIfFromFactory(device, connection));

With shared_ptr would it become like this:

void function2(boost::shared_ptr fti (ftGetIfFromFactory(device, 	 
connection))
{
        ...
        fti->writeAndReadAllData(out,inp);
}

void function1(boost::shared_ptr fti (ftGetIfFromFactory(device, 	 
connection))
{
        function2(data);
}

int main()
{
        boost::shared_ptr<FtInterface> fti (ftGetIfFromFactory(device, 	 
connection));
        function1(fti (ftGetIfFromFactory(device, 		connection));
}

What would be the benefit of using non-const references?

Thank you for helping.

Huub