Re: [Boost-users] Is there such stuff in boost?

From: Max (LoadCom_at_[hidden])
Date: 2008-05-05 21:11:49

>Hi Max & Ravi
>
>Ravi wrote:
>> On Saturday 03 May 2008 09:12:01 pm Max wrote:
>>   
>>>>>      double d0, d1, d2, d3;
>>>>>      boost::array<double &, 4> array = {{d0, d1, d2, d3}};
>>>>>      for(int i=0; i<4; i++) array[i] = i;
>>>>>      assert(d2 == 2);
>>>>>         
>>
>> [snip]
>>
>>   
>>> If it won't take a long time, is it possible to rewrite the above code
>>> snnipet making use of boost.Ref?
>>>     
>>
>> #include <boost/array.hpp>
>> #include <boost/ref.hpp>
>>
>> #include <cassert>
>>
>> int main()
>> {
>>   typedef boost::reference_wrapper<double> double_ref_t;
>>   boost::array<double, 2> array;
>>
>>   double_ref_t d0( array[0] );
>>   double_ref_t d1( array[1] );
>>
>>   array[0] = 1.0;
>>   array[1] = 2.0;
>>   assert( d1 == 2.0 );
>>
>>   d0 += d1;
>>   assert( d0 == 3.0 );
>> }
>>   
>or even:
>
>#include <cassert>
>#include <boost/array.hpp>
>#include <boost/ref.hpp>
>
>int main()
>{
>    double d0, d1, d2, d3;
>    boost::array<boost::reference_wrapper<double>, 4> array = 
>{boost::ref(d0), boost::ref(d1), boost::ref(d2), boost::ref(d3)};
>    for(int i=0; i<4; i++)
>    {
>        array[i].get() = i;
>    }
>    assert(d2 == 2);
>
>    return 0;
>}

Thank you Somerville for your solution. This is exactly what I need!

>
>although this is a slightly unusual construct which might suffer nasty 
>aliasing issues, perhaps a few more details of your requirement might 
>clarify a better approach.

Please decorate on the 'nasty aliasing issues'. For more details of my 
intention, please refer to my previous mail I just posted. I hope ther's
a even more elgent way to get rid of the issues you mentioned.

B/Rgds
Max

>
>-- 
>Bill Somerville
>Class Design Limited
>
>
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