A when is the only defaulting construct that pays attention to the
   current topicalizer regardless of which variable it is associated
   with. All other defaulting constructs pay attention to a fixed
   variable, typically $_. So be careful what you're matching against
   if the given is aliased to something other than $_:

      $_ = "foo";
      given "bar" -> $f {
          if /foo/   { ... } # true, matches against $_
          when /bar/ { ... } # true, matches against $f
      }

</quote>

If I read this carefully, then it implies:

   method foo
   {
     $_ := self # redundant, is bound automatically
     for @.bar -> $f
     {
        if .foo { ... } # calls self.foo
        when .foo {....} # calls $f.foo
     }
   }

Right? So my original example would have worked correctly !?

Dave.