[XPath] [XQuery] Allow argument placeholders on keyword arguments

[rhdunn]

[XPath] [XQuery] Allow argument placeholders on keyword arguments

[michaelhkay]

I'm finding all the new stuff with keyword arguments pretty over-complex already, once you start working out all the detailed rules and test cases, and my instinct is that we've already gone overboard in the design, I would prefer to rein it back a bit rather than going even further.

Is this really needed so often that the existing solution of function($y, $x){math:pow($x, $y)} isn't good enough?

[rhdunn]

That makes sense. This possibility came up when I was implementing parser support for KeywordArgument.

[rhdunn]

While writing things like function($y, $x){math:pow($x, $y)} is possible, I was thinking of possible use cases around bounded variadic functions -- that is where I could see this having more value. That is, instead of writing something like:

f(?, (), (), ?)

or:

->($a, $b) { f($a, collation: $b) }

you could express it more cleanly as:

f(?, collation: ?)

Here, it is clear that you are setting the collation as the second parameter, and can avoid issues where you have the wrong number of defaulted parameters and end up setting the wrong parameter.

[michaelhkay]

The current specification implements this feature so I am closing the issue.