[boost] base class for boost::array

Subject: [boost] base class for boost::array
From: Peter Myerscough-Jackopson (peter.myerscough-jackopson_at_[hidden])
Date: 2010-03-15 12:30:52

Dear all,

 

In using boost::array I have felt the need to pass around boost::array's
of an unknown size (unknown to the function receiving the array). I have
therefore created an abstract base class for boost::array so that I can
create a pointer to a common base class for arrays of different sizes.
Essentially std::vector's of different sizes can be passed into a
function with a fixed prototype, but because boost::array constructs a
different type for each array size, a single fixed prototype cannot be
described such that it can be called with different sizes of
boost::array.

 

In code I can write (toy functions) :

 

double sumTotal(const std::vector<double>* values)

{

   double result = 0 ;

   BOOST_FOREACH(double v, values)

   {

      result += v;

   }  

   return result;

}

 

But I can't write:

 

double sumTotal(const boost::array<double>* values)

{

   double result = 0 ;

   BOOST_FOREACH(double v, values)

   {

      result += v;

   }  

   return result;

}

 

Without the second function being a template function, i.e. I cannot
provide a library that takes a boost::array<double>. With the attached
base class, I could define a function that takes a
boost::array_base<double>.

 

Since, I think, the ability to allow boost::array to be used in this way
is that it requires the use of virtual functions, I have written it so
that the inheritance is optional. It is enabled with a #define before
including array.hpp .

 

Is this useful? (I am aware that I maybe could use a boost::range)

 

Thanks for your time,

 

Peter 

 

Ps. On my current compiler, swap and operator= could not be uncommented
in the array_base class.

PPs. This is my first post to boost dev, please be kind... J

 

Dr Peter Myerscough-Jackopson  -  Senior Engineer

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