class Fish {
    has @.scales;
}

##</code><code>##

class Fish {
  has @!scales;
  method scales () { return @!scales }

  # other stuff it does (not exhaustive)
  submethod BUILD ( :@!scales ){}
  method gist () { … }
  method Capture () { \( :@!scales ) }
}

##</code><code>##

class Fish {
    has @.scales is rw;
}

##</code><code>##

class Fish {
  has @!scales;
  #                v---v
  method scales () is rw { return-rw @!scales }

  # other stuff it does (not exhaustive)
  submethod BUILD ( :@!scales ){}
  method gist () { … }
  method Capture () { \( :@!scales ) }
}

##</code><code>##

my $fish = Fish.new;

$fish.scales = ('green','blue','yellow')

##</code><code>##

class Fish {
    has @.scales;
    multi method scales () { @!scales }
    multi method scales ( +@new ) { @!scales = @new }
}

my $fish = Fish.new;

$fish.scales('green','blue','yellow');
say $fish.scales(); # does not clear it
$fish.scales(()); # clears it

##</code><code>##

class Fish {
    has @.scales;
    method scales ( |c (+@new) ) {
        @!scales = @new if c;
        return @!scales;
    }
}

my $fish = Fish.new;

$fish.scales('green','blue','yellow');
say $fish.scales(); # does not clear it
$fish.scales(()); # clears it

##</code><code>##

class Fish {
    has @.scales;
}

my $fish = Fish.new;

$fish.scales = ('green','blue','yellow');
say $fish.scales();
$fish.scales = (); # clears it