zsh library for demonstrating sequences of commands

showshell.zsh

#!/bin/zsh
## Show shell commands in progress
## Usage:
##   source $thisFile
##
#    show "Explanation" "
#      cmd 1
#      cmd 2"

banner() {
  # If COLUMNS is unset, we'll get 4 ='s ({1..-2})
  local cols=$(($COLUMNS - 2))
  printf "="%.0s {1..$cols}; print
  echo "$@"
  printf "="%.0s {1..$cols}; print
  setopt xtrace
}

trace() {
  PS4='> '
  eval "setopt xtrace; $@"
}

show() {
  banner "${argv[1]}"
  trace "${argv[2,-1]}"
}