Arrays of associative arrays in Zsh

While implementing zwm I hit a small wall, the setup packet of the X protocol contains an array of structs, specifically a list of FORMAT and a list of SCREEN.

Zsh doesn’t support setting arrays or associative arrays into other arrays or associative arrays, so you’re stuck with a single level.

The first thought I had was to set a string with the content of the associative array (which emulates the struct) and then eval it, but that would be kinda slow and most of all, ugly as fuck.

Soon enough enlightenment struck me.

We can set an associative array with a numbered serie of key names, like follows:

local -A map
map=(roots.length 2 roots.1.window 23 roots.2.window 42)

We start from 1 as index because that’s what Zsh uses for indexed arrays.

Now that we have our array of associative arrays, we can loop over them and access them more easily:

integer i
for (( i=1; i <= $map[roots.length]; ++i )); do
  local -A root
  root=("${(@kv)map[(I)roots.$i.*]#roots.$i.}")

  print "root window for root number $i: $root[window]"
done

Ta dah.

Arrays of associative arrays in Zsh [Wednesday, 2012-10-31]