[boost] Re: dynamic_cast for shared_ptr

From: Borgerding, Mark A. (MarkAB_at_[hidden])
Date: 2000-02-08 10:50:48

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

In the linked_ptr class, I have the method dynamic_cast_from
returning get().  This was a change from my initial implementation
which returned a reference to *this.  Small change, but it allows the
user to more easily do a conversion and test in 1 step.

e.g.
if ( myDerived.dynamic_cast_from( myBase ) )  { // dynamic_cast and
test
  //myDerived now holds a non-null, correctly typed ptr
}else {
  //myBase is not a derived type
}

- -- Mark

> -----Original Message-----
> From: Miki Jovanovic [mailto:miki_at_[hidden]]
> Sent: Tuesday, February 08, 2000 10:29 AM
> To: boost_at_[hidden]
> Subject: [boost] dynamic_cast for shared_ptr
> 
> 
> 
> Hello all,
> 
> Here is my proposition for dynamic_cast for shared_ptr. Would this
> be of value?
> 
> public:
>    template<typename Y> shared_ptr& dynamiccast( const 
> shared_ptr<Y>& r
> ) {
>       if ( pn != r.pn ) {
>          dispose();
> 
>          dynamicShare( r.px, r.pn );
>       }
>       return *this;
>    }
> 
> protected:
>    template<typename Y> void dynamicShare( Y* rpx, long* rpn ) {
>       Y *cast_rpx = dynamic_cast<T*>( rpx );
>       if ( rpx == NULL || cast_rpx != NULL ) { // check to avoid
> new() for NULL objects. too much?
>          px = rpx;
>          ++*(pn = rpn);
>       }
>       else { // dynamic_cast failed
>          px = NULL;
>          pn = new long(1); 
>       }
>    }
> 
> 
> Cheers,
> 
> Miki Jovanovic.
> 
> 
> --------------------------------------------------------------
> ----------
> What's better than getting a Great Deal from eGroups?
> Getting a Great Deal from eGroups delivered right to your 
> email in-box!
> http://click.egroups.com/1/1236/1/_/9351/_/950023978/
> 
> eGroups.com Home: http://www.egroups.com/group/boost/
> http://www.egroups.com - Simplifying group communications
> 

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBOKA7XP9Ej8AEXMygEQI4jACfZhD0lUoChuL2ueD2bo57SiZsQmwAn2AI
Of3zwoMJJn4RSyQOUbBSmpkv
=0oXP
-----END PGP SIGNATURE-----