Add an opt-in feature for calling autopep8 at every save.

plugin/python_autopep8.vim

@@ -0,0 +1,28 @@
+
+" This function saves the current window state, and executes Autopep8() with
+" the user's existing options. After Autopep8 call, the initial window
+" settings are restored. Undo recording is also paused during Autopep8 call
+function! s:autopep8_on_save()
+  if get(g:, "autopep8_on_save", 0)
+
+    " Save cursor position and many other things.
+    let l:curw = winsaveview()
+
+    " stop undo recording
+    try | silent undojoin | catch | endtry
+
+    call Autopep8()
+
+    " Restore our cursor/windows positions.
+    call winrestview(l:curw)
+
+  endif
+endfunction
+
+" During every save, also reformat the file with respect to the existing
+" autopep8 settings.
+augroup vim-python-autopep8
+   autocmd!
+   autocmd BufWritePre *.py call s:autopep8_on_save()
+augroup END
+