How can I retain Vim undo history but disallow hiding modified buffers? -

similar this question, want keep undo history when change buffers. however, if use set hidden, vim no longer prompts me when switch buffer changes.

how can retain unsaved buffer prompt retain undo history?

you can use new persistent undo feature in vim 7.3.

set undodir=~/.vim/undodir set undofile 

for details, see documentation at

:help persistent-undo