On Tue, Mar 23, 2004 at 01:22:23PM +0100, Marc Lehmann wrote: > On Fri, Mar 19, 2004 at 02:19:09PM -0800, Manish Singh <yosh@xxxxxxxx> wrote: > > While on that subject, I'm wondering what a good way of representing > > named parameters in scheme and perl would be. Any thoughts? > > This is natural, and common: > > $obj->method (arg1 => value1, arg2 => value2, ...) > > this, too: > > $obj->method (-arg1 => value1, -arg2 => value2, ...) > > as well as this: > > $obj->method (Arg1 => value1, Arg2 => value2, ...) > > All of these can be supported at the same time, and the difference > between them is often seen as a style difference only. > > However, there is no way of using the same method both with named > parameters or not (unless your resort to other syntaxes like $obj->method > (ARG1, value1, ARG2, value2), making ARG1 etc. global or worse). Yeah, that is unfortunate, since the interface should support both named and positional interfaces (and combining the two in one call). > Especially with methods with just a single argument, forcing named > parameters might not be the best thing (OTOH, you can make a difference > between methods with single argument and more, but...). > > Right now, a few things get autodetected because gimp-perl uses strong > typing for the gimp objects (as opposed to e.g. C or scheme). All in all > there would be no problem at all supporting named parameters (There is > even a certain amount of support for that already in gimp-perl), but it > will break existing scripts and make writing scripts slightly more > tedious. Well, this would go hand in hand with a plugin api redo, so scripts are gonna break anyway. > Personally though, I really want named parameters. Not at all because of > me being able to remember arguments better (I think it's actually worse to > have to remember the parameter names), but because it allows me to easily > leave off arguments that can be defaulted. > > Most of these arguments, however, are at the end, so even more important > than named parameters would IMHO be default values for unspecified ones. > > I once reworked the PDB code to allow variable number of arguments but > left the check in for compatibility with existing plug-ins who expect all > or nothing (ignoring the number of arguments actually passed; the API did > provide this already). So what would be a good way for perl to support both named and positional stuff? The only way I can think of still is to use a hashref for named parameters. -Yosh
