[Dune] Weird behaviour of MPIHelper

[Aleksejs Fomins]

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Dear Martin,

Thank you :)
I was assuming for no reason that mpihelper_.getCollectiveCommunication() was giving me a reference to a class stored in subconscious of the MPIHelper, but, obviously, it creates a new class every time.

Sorry for the trouble,
Aleksejs

P.S. Sorry for spam, I forgot to reply to all


On 19/05/15 15:45, Martin Nolte wrote:
> Hi Aleksejs
>
> you're returning a reference to a temporary, so weird behaviour is normal. To my knowledge, however, the compiler should emit a warning in this case. Did you disable / ignore them by accident?
>
> Best,
>
> Martin
>
> On 05/19/2015 03:28 PM, Aleksejs Fomins wrote:
> Dear Dune,
>
> I am having trouble with very basic c++ pointer problem in my curvilinear grid. The file grid.hh contains 2 functions:
>
>      const CollectiveCommunication &comm () const  { return mpihelper_.getCollectiveCommunication(); }
>
>      MPIHelper & mpihelper()  const { return mpihelper_; }
>
> One of them returns the MPIHelper reference, the other the CollectiveCommunication reference.
>
>
> I write a test program:
>
> Grid * grid = factory.createGrid();
>
> std::cout << "rank v1 = " << grid->comm().rank() << std::endl;
> std::cout << "rank v2 = " << grid->mpihelper().getCollectiveCommunication().rank() << std::endl;
>
> the result for a serial run is
> -1183734688
> 0
>
> And the first result puzzles me a lot, as I expect it to be equal to the 2nd one. Otherwise, the grid is functioning well, so it is definitely initialized
>
> Any ideas?
>
> Greetings,
> Aleksejs
>>
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