Main logic

This section handles command-line argument parsing and the main execution flow:

typeset -A args
zparseopts -D -K -E -A args -M -- -help=h

if [[ -n ${args[(I)-h]} ]] {
    print -P "Usage: %B$0%b [option…] <output>"
    echo "Options:"
    echo "    -h, --help                    This message"
    exit 0
} elif [[ -z ${1:-} ]] {
    echo "Error: No output given"
    exit 2
}

We wrap the main body in an anonymous function so that zsh has a scope with which to handle the temporary file we generate:

() {
    readonly output=$1 tmp=$2

local package version footnote

The generated CSV has two columns: package name, and package version.

print '"Package","Version"' >> $tmp

Loop over the defined packages and extract the installed version:

for package ($packages) {
    version=$(dpkg-query -W -f='${Version}' $package)

Note

At some point this won’t be enough, but for now relying on dpkg-query Works For Me™.

Append footnote references to version string, if required:

footnote=${footnotes[$package]:-}
if [[ $footnote ]] {
    footnote=" [#s$footnote]_"
}

Write out the row:

    printf '"|%s|","``%s``%s"\n' $package $version $footnote >> $tmp
}

Atomically replace output file:

mv $tmp $output

Pass the output name and a temporary file to the function:

} $1 =(:)