Re: Return values from gtk2 widget (void) methods

["Peter Haworth" <pmh edison ioppublishing com>]

On Tue, 22 Oct 2002 15:51:23 +0100, Dermot Musgrove wrote:
> goran kirra net wrote:
> > 2. On the other hand it would be nice to have a consistant
> >    return value scheme like "0 (zero)"=failed, "not 0"=success
> >    so we could do perlish things like:
> >    $obj->set_label('xx') && $obj->show;
> I reckon that undef is better for failure as it is not the same as 0.
> eg 0 is returned by gtk_window_get_resizable when the window is not
> resizable (false) - but it represents a successful function call.

Unfortunately, 0 and undef are both false. The DBI gets around this by
returning undef on failure (which is false), and '0E0' on zero-valued
success (which is true, but zero in numeric context). If you're only 
returning a success/fail value without any different success values,
then stick to Perl's 1/'' (or 1/undef) values. There are even &PL_sv_yes
and &PL_sv_no values available in C code for this purpose, and
XSRETURN_YES/XSRETURN_NO macros for XS code.

-- 
        Peter Haworth   pmh edison ioppublishing com
"For example, I could be a sentient PERL script.
 That pretty much assumes that someone brilliant enough to write me
 was also stupid enough to program in PERL. Not a likely explanation."
                -- Terry Lambert