Re: Skipping of defaulted parameters.

On Wed, October 20, 2010 6:58 am, Richard Quadling wrote: > foo(10,, 30); // Parse error. I thought this used to work... > I would argue that by having a null in the arguments, the intent is to > NOT supply a value and have the default value used in the function. Unfortunately, no. There are times when I want to over-ride the default, and shove NULL in as the value... > 1 - Do nothing in core and implement is_null() checking to reinstate > the default value. I believe that this is probably Best Practice in current PHP. Validate your incoming parameters consistent with the intent of the code-base in question. > 2 - Allow null to be supplied and have the default value be used for > the argument. > > foo(10, null, 30); // would output 10, 2, 30 -1 > 3 - New keyword of default or void to specifically indicate the intent > to use the default value for the argument. > > foo(10, default, 30); // would output 10, 2, 30 This seems reasonable to me. > 4 - Allow missing arguments to default. > > foo(10,, 30); // Parse error. Also reasonable. I'd even say both 3&4 together are in keeping with PHP spirit, to allow the lazy scripters to use 10,,30 and the formal developers to use DEFAULT. > Option 4 would probably be the worse one to go for. Looking any number > of languages that support defaults and you will see code like ... > > someFunction(param1,,,,,param7,,,,param11) It does get ugly fast for large numbers of arguments... But any function with more than a handful of arguments is already asking for trouble... At that point you should be passing in a data structure / instance / array or something other than so many parameters. Perhaps a constant like PHP_DEFAULT rather than a new "keyword"? > But using something like _ (yep, underscore), could be a solution here > [4]. Icky. :-) > Option 2, after probably having to reject option 3, would be my > choice. I want null to REALLY mean nothing. Just like it would be in > foo(10). Alas, NULL behaves more like an actual value sometimes, depending on which functions you use... isset versus array_key_exists, for example. -- brain cancer update: http://richardlynch.blogspot.com/search/label/brain%20tumor Donate: https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FS9NLTNEEKWBE