Does decorating a class method that uses super break it?

big_animals.coffee

class Animal
  constructor: (@name) ->

  move: (meters) ->
    alert @name + " moved #{meters}m."

class Snake extends Animal
  move: ->
    alert "Slithering..."
    super 5

class Horse extends Animal
  move: ->
    alert "Galloping..."
    super 45

big = (cls) ->
   old_move = cls::move
   cls::move = ->
      alert "Trips."
      old_move.apply(@)

tom = new Horse "Tommy the Palomino"

big Horse

tom.move()
# Alerts Trips., Galloping..., Tommy the Palomino moved 45m.

Hmm, this doesn't actually work for me, as I noted on twitter:
actually, when I try this code it doesn't properly grab the @name. Ran it in browser, it alerts " moved 45 mph"…
changed alerts to "console.log" and ran in console, got "undefined moved 45mph"
if I make the original move a bound function, it gets name right but then "trips" doesnt run.

Echo @edubkendo's comment in Chrome -- doesn't maintain name, and I wouldn't expect it to since you've lost the reference to this when you call old_move(). Shouldn't be it old_move.call @ or similar?

Binding the function isn't right, either, btw -- it'd bound to this at the time that the class is defined or big is called, which isn't what you want.

Oops. You're right! Just ran into the issue the code I was testing this for. Investigating...

Right, I missed an important piece of scope. I've updated the gist with the correct way to do this. (Note the difference on line 21.)