Re: coderef instead of filename for trace() ?

[Tim Bunce]

On Wed, Dec 13, 2006 at 05:42:03PM -0800, Dean Arnold wrote:
> After a bit more research, I think I've figured out
> how to get the PerlIO object from an SV:
> 
>     IO *io;
> 
>     if (!file)                /* no arg == no change */
>       return 0;
>     /* XXX need to support file being a filehandle object */
>     if (SvROK(file)) {
>     /* DAA must be a filehandle...we hope */
>     /* but how do we tell, and how do we get the PerlIO object from an SV ? 
>     */
>       io = sv_2io(file);
>       if (io) {
>           fp = IoOFP(io);
>       }
>       else {
>           warn("Input trace filehandle is not valid");
>           return 0;
>       }
>     }
>     else { /* do things the old way */ }
> 
> Does that make sense ? (I kyped the code from some Perl/Tk internals)

sv_2io never returns false, it croaks. But since you're only calling it
if SvROK is true, and the croak error is meaningful ("Bad filehandle ...")
I think that's fine.  Also, IoOFP(io) might be false in some odd cases.

So I'd suggest a slight tweak:

      if (SvROK(file)) {    /* assume it's a filehandle */
          io = sv_2io(file);  /* will croak if not */
          if (!io || !(fp = IoOFP(io))) {
              warn("DBI trace filehandle is not valid");
              return 0;
          }
      }
      else { ... }

Will need some tests of course. Both for writing to a plain filehandle
and a tied one.

Thanks Dean!

Tim.