How to extend a method?

[ghost]

Hello. I want to extend existing method when extending a class (just add a new function to it, not owerwrite), but don't know how to do it. Here is an example:

local Object = require "classic"
local A = Object:extend()

function A:new()
  function self.sayHi()
    print("Hi from A!")
  end
end

local B = A:extend()

function B:new()
  B.super.new(self)
  function self.sayHi()
    -- B.super.sayHi() -- not working
    print("Hi from B!") -- overwrites
  end
end

local b = B()
b.sayHi() -- Hi from B only!

[rxi]

Methods should be declared outside of the new function and should use : instead of . when created and called. When calling a super method self should be passed to it:

local Object = require "classic"


local A = Object:extend()

function A:new()
end

function A:sayHi()
  print("Hi from A!")
end


local B = A:extend()

function B:new()
  B.super.new(self)
end

function B:sayHi()
  B.super.sayHi(self)
  print("Hi from B!")
end


local b = B()
b:sayHi()

-- prints:
-- Hi from A!
-- Hi from B!

[ghost]

Thank you!