zsh: stop backward-kill-word on directory delimiter

In zsh, how can I set up the line editor such that backward-kill-word stops on a directory separator? Currently in my bash setup, if I type

cd ~/devel/sandbox

and then hit C-w point will be right after devel/. In my zsh setup, point would be after cd . I'd like to set up zsh so it behaves similarly to bash.

For recent versions of zsh, you can simply add:

autoload -U select-word-style
select-word-style bash

to your zshrc as described in the zsh manual (also man zshcontrib).

Another option is to set WORDCHARS (non-alphanumeric chars treated as part of a word) to something that doesn't include /.

You can also tweak this if you'd prefer ^w to break on dot, underscore, etc. In ~/.zshrc I have:

WORDCHARS='*?_-.[]~=&;!#$%^(){}<>'

A quick google reveals:

Backward Kill

Or, perhaps a better fix:

Bash Style Backward Kill