[Dune-devel] [Dune-Commit] [Commit] dune-common - 2fff527: [Release][Array] Provide a function for creating an array filled with copies of a single element

[Steffen Müthing]

Hi Oliver,

Am 16.12.2013 um 17:07 schrieb Oliver Sander:

> Hi Steffen,
> I suppose the line
> 
>> +    std::cout << "test" << std::endl;
> 
> is not there to stay?

no, not really… thanks for noticing ^^

> 
> Why do I need this method anyway, when I have std::fill?

Because std::fill() (or array.fill(val)) doesn't really help me at all when trying to fix the deprecation warnings in PDELab ;-)
Throughout PDELab, there are several places where a YaspGrid is initialized as a member variable in a constructor, and
in that case creating an array and filling it in a second step just doesn't work. Code like this:

MyObject(…)
  : _grid(Dune::FieldVector<double,dim>(1.0),Dune::fill_array<int,dim>(n),std::bitset<dim>(false),0)
  , ….

Unfortunately, the standard doesn't provide an array constructor that copies a given object to all array elements...

> 
> Is it going to go away when we kill our own array implementation?

Well, we'll need it until the standard gets amended… ;-)

Steffen

> 
> Cheers,
> Oliver
> 
> Am 16.12.2013 17:04, schrieb Steffen Müthing:
>> New commit, appeared at Mon Dec 16 17:04:40 2013 +0100
>> as part of the following ref changes:
>> 
>>    branch refs/heads/master    updated from 9f1a112 -> 2fff527
>> 
>> Browsable version: http://cgit.dune-project.org/repositories/dune-common/commit/?id=2fff527599173a8da0ce38a7c9d7f38053f04122
>> 
>> ======================================================================
>> 
>> commit 2fff527599173a8da0ce38a7c9d7f38053f04122
>> Author: Steffen Müthing <muething at dune-project.org>
>> Date:   Mon Dec 16 17:02:12 2013 +0100
>> 
>>    [Release][Array] Provide a function for creating an array filled with copies of a single element
>> 
>>    The new YaspGrid constructors require an array with the number of cells
>>    in each direction. Unfortunately, there is no array constructor that
>>    takes a single element and copies it to all array elements.
>> 
>>    This patch adds a simple function Dune::fill_array() to do just that.
>> 
>> dune/common/array.hh | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>> 
>> 
>> 
>> diff --git a/dune/common/array.hh b/dune/common/array.hh
>> index cf2cf3a..5b550d3 100644
>> --- a/dune/common/array.hh
>> +++ b/dune/common/array.hh
>> @@ -253,6 +253,23 @@ namespace Dune
>>     return result;
>>   }
>> 
>> +  //! Create an array and fill it with copies of the provided value.
>> +  /**
>> +   * \note This method is Dune-specific and not part of any C++ standard.
>> +   */
>> +  template<typename T, std::size_t n>
>> +  array<T,n> fill_array(const T& t)
>> +  {
>> +    array<T,n> r;
>> +    r.fill(t);
>> +    std::cout << "test" << std::endl;
>> +#if HAVE_RVALUE_REFERENCES
>> +    return std::move(r);
>> +#else
>> +    return r;
>> +#endif
>> +  }
>> +
>>   /** @} */
>> 
>> } // end namespace Dune
>> 
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>> 
> 
> 
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