Re: Function naming: Problems and proposed solution

>  The key is that ALL the keyword arguments are combined into a map,
> which is supplied as the final argument of a function whose signature
expects a map as its last argument.

Then what is the arity of the function? N,   or   N -
count(map:keys($last))     ???

This seems very confusing.

Thanks,
Dimitre

On Wed, Dec 2, 2020 at 8:30 AM Michael Kay <mike@saxonica.com> wrote:

> From a first glance it seems to me that allowing default values for
> arguments (aka keyword arguments or optional arguments) clashes with our
> ability to define function overloads having fewer arguments.
>
>
> I don't think so. The key is that ALL the keyword arguments are combined
> into a map, which is supplied as the final argument of a function whose
> signature expects a map as its last argument.
>
> serialize(X) calls serialize#1
>
> serialize(X, method:='json') calls serialize#2 - it's essentially just a
> shorthand notation for serialize(X, map{'method':'json'}).
>
> serialize(X, method:='json', indent:=true()) also calls serialize#2 - the
> keyword arguments are combined into a single map value, matching the final
> argument in the function signature which accepts a map.
>
> What you can't do using this mechanism is to supply an empty map as the
> second argument. If you want to do that, you just call
>
> serialize(X, map{})
>
> but you don't need to, because the fn:serialize function has been designed
> so this is equivalent to serialize(X).
>
> Michael Kay
> Saxonica
>
> On 2 Dec 2020, at 16:21, Dimitre Novatchev <dnovatchev@gmail.com> wrote:
>
>
>
> Please, prove me wrong.
>
> Thanks,
> Dimitre
>
> Sent from my iPhone
>
> On Dec 2, 2020, at 8:07 AM, Michael Kay <mike@saxonica.com> wrote:
>
> 
>
> On 2 Dec 2020, at 11:27, Tom Hillman <tom@expertml.com> wrote:
>
> serialize($x, method: 'json', indent: true())
>
>
>
> I've had a go at speccing this up: see
> https://htmlpreview.github.io/?https://github.com/qt4cg/qtspecs/blob/master/specifications/xquery-40/html/xpath-40-diff.html
>
> Search for "keyword arguments".
>
> I'm liking it.
>
> (I used ":=" rather than ":" as the punctuation, but it's easily changed)
>
> There's a bug in the grammar -- it allows f( , a:= 3 ) -- but hey, it's a
> first draft.
>
> Michael Kay
> Saxonica
>
>
>