How to keep context(aka this) for a setInterval callback in a coffeescript class

keepcontext.coffee

class ggp
  constructor: (@nm)->
    self = this
    setInterval (->
      self.shownm()
    ),1000
  shownm: ->
    console.log 'my name is ', @nm

g1 = new ggp( 'qq')


#the other way: define a special setInterval() which can accept context

setInterval_withctx = (t, ctx, func)->
  setInterval (->
    func.call ctx
  ),t

class yyp
  constructor: (@nm)->
    setInterval_withctx 1000, @, @shownm
  shownm:->
      console.log 'my name is ', @nm
                                 
g2 = new yyp( 'jj')