Use chpwd instead of precmd hook, and add-zsh-hook

[ericbn]

This triggers z at every working directory change, instead of at every prompt, in zsh. Use add-zsh-hook to set up the _z_chpwd function.

Also, update the async job call inside _z_chpwd. The parenthesis, which do the call in a subshell, are not necessary, and &! makes sure the job is immediately disowned (and there's no output of the process ID or it's termination status). See http://zsh.sourceforge.net/Doc/Release/Jobs-_0026-Signals.html

This code is compatible with zsh versions >= 5.0.

Also update man page and README.

Closes #210

[ericbn]

add-zsh-hook guarantees that the same hook function is not added twice, so removed the [ -n "${precmd_functions[(r)_z_precmd]}" ] test.

[ericbn]

I see that using cmd &! instead of (cmd &) breaks sourcing z.sh in other shells, like in sh. Keeping the original (cmd &) construct is probably a better idea here.

[mcornella]

I would keep using the previous construct to add the function to chpwd, since it supports earlier zsh versions and you don't need to autoload add-zsh-hook. We could use a better, clearer syntax though:

chpwd_functions+=(_z_chpwd)

I have to say that I haven't checked it in other shells though.

[mcornella]

Indeed, dash chokes on that syntax because the parentheses makes it look like a function. We could use the old syntax that we know works everywhere, or we could do

typeset -a chpwd_functions
chpwd_functions+=_z_chpwd

The typeset is to force declare chpwd_functions as an array, otherwise we could get a string if it wasn't defined previously. This one's confirmed to pass the syntax check in bash and dash.

[rupa]

I've been following this discussion with interest - as a bash user, wistful about having a chpwd hook - but for this utility, I think we should stick with prompt command. We're trying to weight by "time spent" in a directory, not just how many times we visited

[ericbn]

Fair enough. I'm closing this then.