Calling ggproto methods
ggproto methods can take an optional self argument: if it is present, it is a regular method; if it's absent, it's a "static" method (i.e. it doesn't use any fields). Imagine you have a ggproto object Adder, which has a method addx = function(self, n) n + self$x. Then, to call this function, you would use Adder$addx(10) -- the self is passed in automatically by the wrapper function. self be located anywhere in the function signature, although customarily it comes first.Calling methods in a parent
To explicitly call a methods in a parent, use ggproto_parent(Parent, self).