Element Command Processing (1)

• Generic requirements:
  • Commands must be valid for the addressed element.
  • Element state must not be contradictory to the execution of the command.
• We would like to be able to write rules according to this pattern:

  rule "element not eligible for command x"
  when
      there is an element command
      - with the code x-ify
      and the commanded element
      - is not a x-able element
  then
      send failed command message "cannot x-ify element"
  end
  
  rule "element eligible for command x"
  when
      there is an element command
      - with the code x-ify
      and the commanded element
      - is a x-able element
  then
      execute command
  end
  

Problem: How can we reduce the number of rules?

Problem: How can we avoid duplicating conditions for error detection and processing rules?