make-closure.vim

function! s:make_counter(init)
  let ret = {"count": a:init} 
  function! ret.countup() dict
    let self.count = self.count + 1
    return self.count
  endfunction
  return ret
endfunction

unlet! c
let c = s:make_counter(0)
echo c.countup()
echo c.countup()
echo c.countup()
echo c.countup()
echo c.countup()