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


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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.
>
>
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