Re: [Boost-users] [multi_array] operator= requires resize - why?

Subject: Re: [Boost-users] [multi_array] operator= requires resize - why?
From: Rhys Ulerich (rhys.ulerich_at_[hidden])
Date: 2012-06-04 08:43:24

> Ronald Garcia wrote
>> If multi_array's assignment
>> had different semantics from the rest of the arrays, then assignment
>> would behave very differently generic algorithms depending on whether
>> you pass a multi_array or a different function.
>
> I cannot get why introducing automatically resizing would cause any trouble
> for any generic algorithm, since it would not prevent from calling the
> assignment for objects that do have the same shape. Do you have any precise
> example to explain why it would be such a trouble?

A total guess...  You have two 4D multi_arrays used in an algorithm.
Algorithm checks that their fastest dimension has the same size.  It
does.  The algorithm is called recursively on a 3D subproblem.  The
algorithm checks that the two 3D sub-multi_arrays have a fastest
dimension with the same size.  They don't.  Now what should the
generic algorithm do?  If it resizes the 3D subproblem bad things
happen to the original 4D multi_array.

- Rhys