Re: [Boost-users] mpl for_each copies function object (bug?)

From: Sebastian Weber (sebastian.weber_at_[hidden])
Date: 2008-05-20 08:14:17

Hi Ovanes!

Ahh, sure you are right. I got too much used to fusion 
notion which I think is superior in this point. But I guess 
there are some reasons for the ref-wrapping stuff which works.

Thanks again.

Sebastian

Ovanes Markarian schrieb:
> Hi, Sebastia!
> 
> Please use boost::reference_wrapper to disable copying...
> 
> mpl::for_each< mpl::vector<bool, double>, worker_t& >(boost::ref(workit));
> 
> 
> Hope that helps.
> 
> Ovanes
> 
> On Tue, May 20, 2008 at 8:35 AM, Sebastian Weber 
> <sebastian.weber_at_[hidden] 
> <mailto:sebastian.weber_at_[hidden]>> wrote:
> 
>     Hi there!
> 
>     I'm currently struggling with mpl::for_each: It copies my
>     function object no matter what I do. Here is some dummy code:
> 
>     worker_t workit; // the worker object which recieves the
>     different types and has an internal state
> 
>     mpl::for_each< mpl::vector<bool, double>, worker_t& >(workit);
> 
>     Now, the workit object becomes copied which is clear from
>     the sources. However, I explicitly requested it not to be
>     copied by the hint of giving the reference worker_t& as a
>     template parameter.
> 
>     Maybe this behaviour is wanted, but I do not see the reason.
>     In the fusion-world this is the  way to go if one wants to
>     prevent copying of function objects.
> 
>     Is this now a bug or a feature and how can I fix it (quick).
> 
>     Greetings,
> 
>     Sebastian
> 
> 
> 
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