Re: recent change for "string enum varibles"

[Jaroslav Hajek]

On Tue, May 18, 2010 at 8:04 AM, John W. Eaton <address@hidden> wrote:
> In the recent change for "string enum variables", you introduced a
> function
>
>  octave_value
>  set_internal_variable (int& var, const octave_value_list& args,
>                         int nargout, const char *nm, const char **choices,
>                         int nchoices)
>
> Which relies on NCHOICES properly counting the number of elements of
> CHOICES.  I've generally tried to avoid things like this in Octave
> since it is easy for the number of elements of a variable wrong.  If
> there is some good reason to avoid using a string_vector, std::list
> (or some other  standard container),

The problem is that you can't (in C++98) supply static initializers
for containers, so you either need to recreate them each time
the function is called (unnecessarily slow), or use an extra static
function to init them (clumsy).

> then how about using 0 to mark
> the last element of CHOICES so you don't have to count the number
> of elements but instead look for 0 as the end of the array?
>

That's a good idea. This is safer and the extra work on user side is minimal.

-- 
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz