This is a known issue, as there is no native support for attribute binding this way. There’s quite some code in the setting working around this issue :-(
> On 15 Sep 2016, at 20:49, Zoffix Znet (via RT) <perl6-bugs-follo...@perl.org> > wrote: > > # New Ticket Created by Zoffix Znet > # Please include the string: [perl #129278] > # in the subject line of all future correspondence about this issue. > # <URL: https://rt.perl.org/Ticket/Display.html?id=129278 > > > > #Doesn't work: > <TestNinja> m: class { has int $!n = 0; method x ($!n) {} }.new.x: 42 > <camelia> rakudo-moar 2c95f7: OUTPUT«Cannot modify an immutable int in > method x at <tmp> line 1 in block <unit> at <tmp> line 1» > > # But does, if we use a temp var: > <TestNinja> m: class { has int $!n = 0; method x ($n) {$!n = $n} }.new.x: 42 > <camelia> rakudo-moar 2c95f7: ( no output )
