Re: const gsl_vector *

[John D Lamb <J dot D dot Lamb at btinternet dot com>]

On 13/08/14 01:03, Gerard Jungman wrote:
> The constness of gsl_vector interfaces makes no sense. This is a
> simple observation, but it seems to have escaped discussion for
> over a decade. Consider the following code (file attached).
>
>   #include <gsl/gsl_vector.h>
>
>   void notwhatyouthink(const gsl_vector * v)
>   {
>     v->data[0] = 42.0;
>   }
>
> The goals:
>    - const-correctness
>    - no "doubling" of interfaces
>    - an architecture where views are central
>    - memory management factored out (allocation/deallocation)
>
> Ideas?

I mainly use C++. But I think C now works so that you could use

gsl_vector* const v

in place of a

const gsl_vector* v

argument, and get the desired result.

I don’t know if there would be unintended consequences of rewriting the 
arguments of the GSL functions this way. I know that C can’t handle both of

int function( const gsl_vector* v );
int function( gsl_vector* const v );

in the same code. So it would need a rewrite.

One issue would be that if the code were rewritten any code that passed 
a const gsl_vector* argument would cause a compilation failure. The 
workaround might be to use a

gsl_vector const* const v

argument. But I don’t know if that would cause problems, for example 
with older compilers.

--
John D Lamb