Re: casting

[Søren Hauberg]

John W. Eaton skrev:
> On 12-Mar-2007, David Grohmann wrote:
>
> | 
> | Thank you. I will give that a  shot.
> | 
> | Søren Hauberg wrote:
> | > How about this function:
> | >
> | > function B = cast(A, newclass)
> | >   B = feval(newclass, A);
> | > endfunction
>
> To avoid the feval and to also be able to detect invalid class names,
> I used the following:
>
> function retval = cast (val, typ)
>
>   if (nargin == 2)
>     if (ischar (typ))
>       switch (typ)
>         case "int8"
>           retval = int8 (val);
>         case "uint8"
>           retval = uint8 (val);
>         case "int16"
>           retval = int16 (val);
>         case "uint16"
>           retval = uint16 (val);
>         case "int32"
>           retval = int32 (val);
>         case "uint32"
>           retval = uint32 (val);
>         case "int64"
>           retval = int64 (val);
>         case "uint64"
>           retval = uint64 (val);
>         case "double"
>           retval = double (val);
>         case "single"
>           retval = single (val);
>         otherwise
>           error ("cast: invalid type name `%s'", typ);
>       endswitch
>     else
>       error ("cast: expecting type name as second argument");
>     endif
>   else
>     print_usage ();
>   endif
>
> endfunction
Just a few stupid questions :-)
Is feval really so slow that you switch-case is faster? If I had to do 
input checking in my code I would just have added something like

if (!any(strcp(typ, {"int8", "int16", "uint8", (you get the idea...)})))
  error("cast: second argument must be the name of a builtin type");
endif

followed be the call to feval. I would just guess that it's more easy to 
maintain because it's less code.

Also, I that you handle the "single" type in your code. Does octave 
support "single" now?

Is the "cast" function in cvs now?

Søren