> On 17 Nov 2017, at 22:47, Elizabeth Mattijsen <l...@dijkmat.nl> wrote:
>> On 17 Nov 2017, at 20:09, Fernando Santagata <nando.santag...@gmail.com>
>> wrote:
>> I tried to use the code you suggested:
>>
>> sub trait_mod:<is>(Attribute:D \attribute, :&proxy!) {
>> attribute.package.^add_method(attribute.name, my method () { proxy($_) })
>> }
>>
>> class A {
>> has $!a is proxy({ $^a * 2 });
>> has $!b is proxy({ $^a * 3 });
>> }
>>
>> my A $a .= new;
>> $a.a = 21; # <-- No such method 'a' for invocant of type 'A'
>> say $a.a;
>> $a.b = 21;
>> say $a.b;
>>
>> But I got an error on the first assignment.
>> What am I doing wrong?
>
> Ok, finally had some time to figure this out more deeply. My result:
> =====================================
> sub trait_mod:<is>(Attribute:D \attribute, :&proxy!) {
> my $name = attribute.name;
> my $method = $name.substr(2);
> attribute.package.^add_method($method, my method ($SELF:) is raw {
> use MONKEY-GUTS;
> Proxy.new(
> FETCH => { nqp::getattr(nqp::decont($SELF),$SELF.WHAT,$name) },
> STORE => -> $, $value {
> nqp::bindattr(nqp::decont($SELF),$SELF.WHAT,$name,proxy($value))
> }
> )
> });
> }
And this would be the version without MONKEY-GUTS, moritz++
====================================
sub trait_mod:<is>(Attribute:D \attribute, :&proxy!) {
attribute.package.^add_method(attribute.name.substr(2), my method ($SELF:) {
Proxy.new(
FETCH => { attribute.get_value($SELF) },
STORE => -> $, \value { attribute.set_value($SELF,proxy(value)) }
)
});
}
====================================
Turns out the Attribute class has a set_value and get_value method. Which
moritz++ pointed out to me on #perl6-dev. So no need to get gutsy!
Liz
