Re: [Boost-users] shared_ptr to this

Subject: Re: [Boost-users] shared_ptr to this
From: Steffen Heil (Mailinglisten) (lists_at_[hidden])
Date: 2013-09-10 11:41:44

Hi

In your case a is a stack variable that should never be deleted.
You should never use a shared_ptr for that.

Let's assume, your local variable a was only for showing the problem, but in fact your real code only uses heap allocated objects...

Then you should NOT pass a void* to the constructor of Data but a shared_ptr<void>.
The caller would then keep that shared_ptr around until it's own calls to the object are done...
See modified code below.

Regards,
  Steffen

> #include <boost/bind.hpp>
> #include <boost/thread/thread.hpp>
> #include <time.h>
> 
> 
> struct Data
> {
>     Data( boost::shared_ptr<void>* p ) :
>     ptr( p )
>    {
>    }
> 
>     boost::shared_ptr<void> ptr;
> };
> 
> void threadA( Data* d )
> {
>     boost::shared_ptr<void> ptr( d->ptr );
>     delete d;
>     // use ptr
> }
> 
> class A : public boost::enable_shared_from_this<void>
> {
>    public:
>    void init_thread()
>    {
>      Data* data = new Data( shared_from_this<void>() );
>      boost::thread t( boost::bind( threadA, data ) );
>    }
> 
>      void sleep()
>      {
>     timespec req;
>     req.tv_sec = 3;
>     req.tv_nsec = 0;
>     nanosleep( &req, NULL );
>      }
> };
> 
> int main()
> {
>    {
>    A *a = new A();
>    boost::shared_ptr<void> x = a;
>    a->init_thread();
>    a->sleep();
>    } // end of scope of x
>    return 0;
> }
>