Fast word count function in Vim

Question

I am trying to display a live word count in the vim statusline. I do this by setting my status line in my .vimrc and inserting a function into it. The idea of this function

Answer 1

I took the bulk of this from the vim help pages on writing functions.

function! WordCount()
  let lnum = 1
  let n = 0
  while lnum <= line('$')
    let n = n + len(split(getline(lnum)))
    let lnum = lnum + 1
  endwhile
  return n
endfunction

Of course, like the others, you'll need to:

:set statusline=wc:%{WordCount()}

I'm sure this can be cleaned up by somebody to make it more vimmy (s:n instead of just n?), but I believe the basic functionality is there.

Edit:

Looking at this again, I really like Mikael Jansson's solution. I don't like shelling out to wc (not portable and perhaps slow). If we replace his UpdateWordCount function with the code I have above (renaming my function to UpdateWordCount), then I think we have a better solution.