custom_exception.rb

class CustonException < StandardError
end

class CustonError < StandardError
end

def error_source(exception=true)
  raise CustonException.new("Exception from error_source") if exception
  raise CustonError.new("Error from error_source") 
end

def error_handler(flag=true)
  begin
    error_source(flag)
  rescue CustonException => e
    puts "in exception_hander"
    p e
  ensure
    puts "ensure clause in error_handler"
  end
end

def error_relay(flag=true)
  begin
    error_source(flag)
  rescue => e
    puts "#{e} is relaied"
    raise e
  ensure
    puts "ensure clause in error_relay"
  end
end

begin
  error_handler
  error_handler(false)
rescue => e
  puts "at global"
  p e
end

begin
  error_relay
rescue => e
  puts "at global"
  p e
end