Re: Unnecessary initialization in octave_matrix::double_value ?

[John W. Eaton]

On 08/28/2016 04:12 AM, Julien Bect wrote:
> Hi all,
>
> I have a (probably naive) C++ question concerning the implementation of
> octave_matrix::double_value ().
>
> It is currently written like this:
>
> double
> octave_matrix::double_value (bool) const
> {
>   double retval = lo_ieee_nan_value ();
>
>   if (is_empty ())
>     err_invalid_conversion ("real matrix", "real scalar");
>
>   warn_implicit_conversion ("Octave:array-to-scalar",
>                             "real matrix", "real scalar");
>
>   retval = matrix(0, 0);
>
>   return retval;
> }
>
> I don't understand the point of initializing retval with the result of
> lo_ieee_nan_value ().  Would it be correct to simply write:
>
> double
> octave_matrix::double_value (bool) const
> {
>   if (is_empty ())
>     err_invalid_conversion ("real matrix", "real scalar");
>
>   warn_implicit_conversion ("Octave:array-to-scalar",
>                             "real matrix", "real scalar");
>
>   return matrix (0, 0);
> }

You are right, that initialization is no longer needed.  It is left over 
from when the error function did not throw an exception but just printed 
a message and set a global warning state, then returned.  So in the old 
days the function would always return something.  A NaN was better than 
undefined.  Although much of the work has been done to adapt to the new 
way that error works, there are still many small things like this to 
clean up.

jwe