prezto/modules/helper/functions/add-zsh-trap

#
# Provides for trapping UNIX signals and calling callback functions when a trap
# is triggered.
#
# Authors:
#   Sorin Ionescu <sorin.ionescu@gmail.com>
#

# Adds a function name to a list to be called when a trap is triggered.
function add-zsh-trap {
  if (( $# < 2 )); then
    print "usage: $0 type function" >&2
    return 1
  fi

  if [[ -z "$signals[(r)$1]" ]]; then
    print "$0: unknown signal: $1" >&2
    return 1
  fi

  local trap_functions="TRAP${1}_FUNCTIONS"
  if (( ! ${(P)+trap_functions} )); then
    typeset -gaU "$trap_functions"
  fi
  eval "$trap_functions+="$2""

  if (( ! $+functions[TRAP${1}] )); then
    eval "
      function TRAP${1} {
        for trap_function in \"\$TRAP${1}_FUNCTIONS[@]\"; do
          if (( \$+functions[\$trap_function] )); then
            \"\$trap_function\" \"\$1\"
          fi
        done
        return \$(( 128 + \$1 ))
      }
    "
  fi
}

add-zsh-trap "$@"