Hi Mark,
get_value won't give you what you expect. It's use is narrowly limited to trait
'is handles' and method .perl. Besides, are you sure all of your attributes
will be considered as belonging to XML? I mean, won't there be need for utility
attributes serving exclusively internal needs of a class? If so, then the best
solution is to create a trait for an attribute and have it like:
has $.SerialNumber is xmlattr;
The trait would then install an accessor which would do what you need.
Best regards,
Vadim Belman
> On Sep 8, 2019, at 12:41 PM, Mark Devine <m...@markdevine.com> wrote:
>
> Perl6 Community,
>
> How do I properly wrap an attribute’s ^get_value method in TWEAK? If a
> condition exists, I’d like to wrap all (:local) attributes so that they can
> do some extra work.
>
> The module that I’m working on has classes/attributes for hundreds of fields
> in dozens of different, big XML files -- there’s a lot. And XML is easily
> extended, so I may very well be adding hundreds more attributes in the
> future. I would very much prefer to preserve the automatic accessor behavior
> of ‘has $.attr;’ versus writing a billion set/get accessors myself – truly
> prohibitive. Wrapping seems the elegant/extensible approach.
>
> class System {
> has $.SerialNumber;
> submethod TWEAK {
> for self.^attributes(:local) -> $attr {
> self.$attr.^get_value.wrap: { say 'in ' ~ $attr.name ~ "'s
> get_value"; nextsame; };
> }
> self;
> }
> }
> say System.new(:SerialNumber('ABCDEFG')).SerialNumber;
>
> # OUTPUT: No such method 'CALL-ME' for invocant of type 'Attribute'
>
> I know the above .wrap is probably misguided, but it sort of demonstrates
> what I’m trying to do.
>
> I’m not finding the proper approach. Any hints? Any tutorials? Any
> existing examples in the ecosystem that I could mimic?
>
> Thanks,
>
> Mark
