vimrc snippet to automatically strip trailing whitespace in code files

vimrc

" a function that preserves the state
" see http://technotales.wordpress.com/2010/03/31/preserve-a-vim-function-that-keeps-your-state/
function! Preserve(command)
  " Preparation: save last search, and cursor position.
  let _s=@/
  let l = line(".")
  let c = col(".")
  " Do the business:
  execute a:command
  " Clean up: restore previous search history, and cursor position
  let @/=_s
  call cursor(l, c)
endfunction

autocmd BufWritePre *.rb,*.js,*.coffee,*.rdoc,*.rake,Rakefile,Gemfile,Thorfile,Guardfile,config.ru,*.html,*.css,*.md,*.markdown,*.textile,*.html.erb,LICENSE,*.treetop :call Preserve("%s/\\s\\+$//e")