[Trilinos-Users] Teuchos::RCP behavior

[Holger Brandsmeier]

Andrea,

indeed you are running in serious trouble here ...

> void assign(Teuchos::RCP<UInt> & P)
> {
>   UInt i = 4;
>   P = Teuchos::rcpFromRef(i);
>   cout << *P << endl;
> }
So you generate a class i of type "UInt" and P is a pointer on that
piece of memory. Once `assign` exists `i` is deleted and `P` referes
to invalid memory. This is bad.

Why don't you do:
void assign(Teuchos::RCP<UInt> & P)
{
   UInt* i = new UInt();
   *i = 4;
   P = Teuchos::rcp(i);
   cout << *P << endl;
 }

Or at least tell us what you try to achieve.

-Holger


On Fri, May 10, 2013 at 3:15 PM, Villa Andrea (RSE)
<Andrea.Villa at rse-web.it> wrote:
>
> I've implemented a very simple test code:
>
> void assign(Teuchos::RCP<UInt> & P)
> {
>   UInt i = 4;
>   P = Teuchos::rcpFromRef(i);
>   cout << *P << endl;
> }
>
> int main(int argc, char *argv[])
> {
>   Teuchos::RCP<UInt> P;
>   assign(P);
>
>   cout << *P << endl;
>   cout << "count: " << P.total_count() << endl;
> }
>
> I think that this is a non-correct usage of the RCP class, since a temporary
> reference is passed to P. In fact I get the following output:
>
> 4
> 0
> count: 1
>
> However even I have built Trilinos using
> -D Teuchos_ENABLE_DEBUG:BOOL=ON \
> -D Teuchos_ENABLE_DEBUG_RCP_NODE_TRACING:BOOL=ON \
> no exception is thrown. Am I missing something?
>
> Thank you very much.
> Andrea Villa.
>
>
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-- 
Holger Brandsmeier, SAM, ETH Zürich
http://www.sam.math.ethz.ch/people/bholger