Automatically adds the utf-8 magic comment to ruby files

ruby_magic_comment.vim

" Adds the ruby magic comment to file
" Ignores SheBang-ed files
fun! AddMagicEncodingComment()
  let line = getline(1)
  let pos = getpos(".")
  exec "normal gg"
  if(match(line,"#!")) > -1
    let line = getline(2)
    exec "normal j"
  endif
  if(match(line,"encoding")) == -1
    exec "normal O# -*- encoding : utf-8 -*-"
    if pos[1] == 1
      " new file:
      call setpos(".", [pos[0], 2, pos[2], pos[3]])
    else
      " existing file
      call setpos(".", pos)
    endif
  endif
endfun
au FileType ruby call AddMagicEncodingComment()