Using Vim's persistent undo?

Question

One of the new features in Vim 7.3 is 'persistent undo', which allows for the undotree to be saved to a file when exiting a buffer.

Unfortunately, I haven't quite been able to get it properly enabled, or I must be using it wrong. Here's what I've tried so far:

I added the following to ~/.vimrc

set undofile                " Save undos after file closes set undodir=$HOME/.vim/undo " where to save undo histories set undolevels=1000         " How many undos set undoreload=10000        " number of lines to save for undo 

After this, I supposedly should be able to open any file, edit it, then save-close it, and when I open it again I should be able to undo/redo as if I'd never left. Unfortunately, this doesn't seem to be the case, as no undofile is ever written.

Notes:

1. I'm on Win 7 using Vim 7.3 from the Vim without cream project. Persistent undo is baked-in.

2. $HOME/.vim/undo exists on my file system

Answer 1

Put this in your .vimrc to create an undodir if it doesn't exist and enable persistent undo. Tested on both Windows and Linux.

" Put plugins and dictionaries in this dir (also on Windows) let vimDir = '$HOME/.vim'  if stridx(&runtimepath, expand(vimDir)) == -1   " vimDir is not on runtimepath, add it   let &runtimepath.=','.vimDir endif  " Keep undo history across sessions by storing it in a file if has('persistent_undo')     let myUndoDir = expand(vimDir . '/undodir')     " Create dirs     call system('mkdir ' . vimDir)     call system('mkdir ' . myUndoDir)     let &undodir = myUndoDir     set undofile endif 

Answer 2

I tried this in my _gvimrc:

" Persistent undo try      set undodir=C:\vim\undodir     set undofile catch endtry 

It started working as advertised when I deleted the try-catch bracket, thus:

" Persistent undo set undodir=C:\vim\undodir set undofile 

I had to create the directory.