3.5.3 OO languages: Dramatic Chord

Motivation

OO’s systems should be very easy to customize. Ideally, centralized controllers are verboten. If there are special cases, they need to be specializations in leaf classes.

So, this week, we’ll try to specialize the processing you wrote to last year.

Usual Stuff

Setup

Perform the weekly set up instructions for project 2, homework c. If you find that you are missing any files, copy them over from 2/b.

CAUTION: do not cp 2/b/* as that may copy the magic .svn directory into 2/b (thus messing up your repo). Copy them over the old-fashioned way (e.g. cp ../a/gold.lisp .) then svn add them.

What to Hand In

Report:

• All the lisp functions you’ve written;
• The ‘repl.txt’ coming from your REPL session where you run (main), this time with the "dramatic chords" you code below;
• Your svn log showing all the commits generated as part of this week’s homework;
• A file containing your deftests for all parts of the following. At least five tests per team member spread out if files with member names.

Background

Consider the following list of atoms in the sci fi grammar:

->                      Understand              extraGalactic
AndAre                  WantSomething           extraterestrial
AndTakeAFewAndLeave     WantWomen               fallsIntoSun
AndThen                 Which                   freezes
Attack                  WhichEtc                giant
Beings                  Whichetc                hungry
ButEtc                  aCrowdOfPeasants        invent
Catestrophe             aCuteLittleKidConvinces isAttackedBy
Catestrophes            aPriestTalksToThemOfGod isRescuedBy
Collision               almostEverybody         isStruckByAGiant
Denomument?             and                     killed
Denoument               andAre                  lookUponUsAsASourceOfNo
Denoument?              andAreNot               lunar
DenoumentOrHappyEnding  andIsDestroyed          martian
Dine                    andMagicallySaved       misunderstandUs
DoSomething             andTheyDie              not
Earth                   andTheyGetMarriedAndLiv radioactive
EndSadOrHappy           andTheyLeave            reptiles
Ending                  andTheyTurnIntoDisgusti scientists
Extraterestrial         areFriendly             soScientistsInventAWeap
Floater                 asteroid                soTheyEatUs
GoOn                    be                      soTheyKillUs
HappyEnding             blobs                   soTheyPutUsUnderABenign
Hungry                  bugs                    somePeople
IsStressed              burnsUp                 superbeings
Killer                  but                     the
Killers                 butIsSaved              theAirForce
PossibleMegaDeath       butIsSavedBy            theArmy
Rescued                 butMisunderstood        theAtomBomb
Resuced                 butTheyDieFromCatchingA theCoastGuard
Saved                   by                      theMarines
Science                 can                     theNavy
SeEtc                   cloud                   theyFallInLoveWithThisB
Sizes                   comet                   tiny
SoEtc                   dies                    understandUsAllTooWell
Some                    discover                us
SomeOne                 earth                   wantOurWomen,
SomeSaved               eat                     whichFails
Start                   enormous                whichKillsThem
TryToKill               everybody               whichTurnsThemIntoDisgu
UnderStand              everybodyDies           who

Note that if some of these atoms are used in any Hollywood blockbuster, there there will be side-effects. For example:

• whichTurnsThemIntoDisgustingLumps: there is an "ooohhh.... yuck" sound.
• PossibleMegaDeath: "oh no!!! (screaming)".
• butTheyDieFromCatchingACold "ah, tissue! (thud)".
• aCuteLittleKidConvincesThemPeopleAreOk "Gee Mr alien, sometimes I get scared when I meet knew people too, like one time, when I went to a new school... I kinda peed my pants. But the teacher was real nice about it and now I have fun there. So I’m sorry we blew up your breeding colony and killed 1,000,000,000 of your relatives and all the royal eggs but we’re real sorry and if you gave us half a chance I’m sure we can be friends".

Your job is to code up those side-effects, in an object-oriented manner.

What to do

• Register a side-effect for 20 of the above atoms. Use LISP’s property lists (which lets you assign something to a field of a symbol):

  (defun sidefx (sym fx)
         (setf (get sym 'fx) fx))
  ;e.g.
  (sidefx 'butTheyDieFromCatchingACold "ah, tissue! (thud)")
  (sidefx 'PossibleMegaDeath}: "oh no!!! (screaming)")
  

  Now you can check if a symbol has side effects;

  (defun sidefxp (sym)
         "if no sidefex, just return empty string"
         (or (get sym 'fx nil)
             ""))
  

• Create sub-classes of *terminal* for *humble* and *loud* (the difference being that only *loud* instances hold the side effects).
• Modify your phrase->instance function that generates either *loud* or *humble* instances. Yes, this code will need an "if" statement but "if"s outside of OO land are unavoidable.
• Test the above on a tiny grammar (two or three phrases). Make sure your grammar has "ands" and "or" in the body.

This document was generated on April 19, 2011 using texi2html 5.0.