simple event/exception handling for bash using 2 simple functions. Handy to keep your bash code compact, responsive and extendable. The advantage of this is that it prevents a lot of if/else code.

exceptions.bash

# simple event / exception handling in bash
#
# onFoo(){
#   echo "onFoo() called width arg $1!"
# }
#
# onExit(){
#   echo "onExit called!"
# }
#
# doBar(){                                                                                                                                #   shift;                                                                                                                                #   echo "foo was called with $1 $2"
# }
#
# foo(){
#   event FOO_OCCURED xyz
# }
#
# init_eventlistener
#
# on FOO_OCCURED onFoo
# on EXIT onExit
# on foo doBar
#
# foo 123 abc
#
# OUTPUT:
#   foo was called with 123 abc
#   onFoo() called width arg xyz!

 declare -A LISTENERS
 
 init_eventlistener(){
      event(){
        E=$1; shift; [[ "$E" == "DEBUG" ]] && E="${BASH_COMMAND// */}"
        for listener in "${LISTENERS[$E]}"; do 
          [[ "${#listener}" == 0 ]] && continue;
          eval "$listener $@ ${BASH_COMMAND}"; 
        done
      }

      on(){
        if ! test "${LISTENERS['$1']+isset}"; then LISTENERS["$1"]=""; fi
        LISTENERS["$1"]+="$2 " # luckily functionnames never contain spaces
      }
      # redirect traps to events
      for i in EXIT SIGINT SIGTERM DEBUG; do trap "event $i" $i; done
  }