passing auto_ptr as shared_ptr
 

Hi

I would like to pass std::auto_ptr as boost::shared_ptr.
When I do that I receive the following compile error:
conversion from ‘std::auto_ptr<Human>’ to non-scalar type ‘boost::shared_ptr<Human>’ requested

How can I do that correctly ?

#include <memory>
#include <boost/shared_ptr.hpp>

using namespace std;
using namespace boost;

class Human {};

void fun (shared_ptr<Human> s) {}

int main(void)
{
auto_ptr<Human> hAP (new Human);
fun (hAP);

return 0;
}

thanks for help

Re: passing auto_ptr as shared_ptr
 

On 12/22/2012 7:07 AM, Jarek Blakarz wrote:
> I would like to pass std::auto_ptr as boost::shared_ptr.

You can't. Those are unrelated types.

> When I do that I receive the following compile error:
> conversion from ‘std::auto_ptr<Human>’ to non-scalar type ‘boost::shared_ptr<Human>’ requested
>
> How can I do that correctly ?

What's your definition of "correctly"?

> #include <memory>
> #include <boost/shared_ptr.hpp>
>
> using namespace std;
> using namespace boost;
>
> class Human {};
>
> void fun (shared_ptr<Human> s) {}
>
> int main(void)
> {
> auto_ptr<Human> hAP (new Human);
> fun (hAP);
>
> return 0;
> }

'std::auto_ptr' template has a 'get' function that returns the actual
pointer to the object. That member doesn't release the ownership, (like
the 'release' member would). I don't know how 'shared_ptr' is
constructed, but it probably take a naked pointer as its argument. So, try

fun(hAP.get());

V
--
I do not respond to top-posted replies, please don't ask

Re: passing auto_ptr as shared_ptr
 

On Saturday, December 22, 2012 2:37:26 PM UTC+1, Paavo Helde wrote:
> Jarek Blakarz <jumianek@gmail.com> wrote in
>
> news:4596c2d7-8547-47f9-835c-659a2ccc5bb4@googlegroups.com:
>
>
>
> > Hi
>
> >
>
> > I would like to pass std::auto_ptr as boost::shared_ptr.
>
> > When I do that I receive the following compile error:
>
> > conversion from ‘std::auto_ptr<Human>’ to non-scalar type
>
> > ‘boost::shared_ptr<Human>’ requested
>
> >
>
> > How can I do that correctly ?
>
>
>
> You can't. The lifetime of the object is managed either by the auto_ptr or
>
> shared_ptr mechanism. You have to choose which one you want to use, nothing
>
> good would happen if both mechanisms attempted to manage the object at the
>
> same time.
>
>
>
> However, you can easily transfer the ownership from an auto_ptr to a
>
> shared_ptr, if that's what you want to do:
>
>
>
> auto_ptr<Human> hAP (new Human);
>
>
>
> shared_ptr<Human> s(hAP.release());
>
>
>
> Note that hAP is now NULL and is not useful for anything any more.
>
>
>
> hth
>
> Paavo

The transfer of ownership from auto_ptr to shared_ptr makes sense. The
following 2 member functions have been defined inside a shared_ptr to
accomplish that:
explicit shared_ptr(std::auto_ptr<Y> & r): px(r.get()), pn()
shared_ptr & operator=( std::auto_ptr<Y> & r )

I have a feeling that the fun(hAP) also makes sense and that's why I feel some
kind of inconsistency why the conversion operator has not been defined.

Please correct me if I'm wrong.