Q0
        Set up
                : svn export http://unbox.org/wisp/var/timm/10/310/src/st/3/c
                : svn add c
                : svn commit -m "3c ready to go"
                :
For each of the following questions, add lines like this to "run"
        printf "\n===== 3/c/q1 ========================\n\n"
        cat myGrammarFilesUsedInThisExample.rules
        cat myCodeThatAnswersThisQuestion.st
        execute
                : where "execute" is the "test" command shown below.
Q1	
	Background
		: In non-OO, data are dead structs that
		: get manipulated by puppet masters (the functions). In OO, the data
		: "structs" (really, classes) are the masters and all functionality
		: lives inside the appropriate class.
		:
		: For example, consider the problem of building the attributed
		: grammars. In all our other implementations, we stored them
		: externally in some hash-table or array. In OO, that is wrong-headed.
		: The fact that we are to cache something, and even the cache value,
		: can be defined inside Rule. So, code up the attributed
		: grammar code, and do it the OO-way way:
	Hints:
		: Create sub-classes of Rule for SimpleRule and CachedRule. SimpleRule
		: is the same as Rule but CachedRule has a "cached" value. 
		:
		: Add some reset code so that you can spin over all the rules and
		: blast their cache.
		:
		: Alter rewriteSome: in Grammar such that the selection code moves
		: inside Rule.
		:
		: After Rule such that SimpleRules do what they currently do while
		: CacheRule returns the cached value, if it exists. Otherwise, it
		: finds a rewrite and caches it.
		:
		: Alter Tag.st so  that when an attributed rule is meet, extra messages 
		: are send to Grammar so it knows to create a Rule 
	Write
		: Adapt your Smalltalk grammar to handle attributed grammars. For such grammars,
		: some of the productions are not "a -> RHS" but "a = RHS". For
		: such rules, the rhs is a set of single atoms; e.g
		: Article = the. terminal. If that rule is selected,
		: then an attribute is fixed to one of those values.
		:
		: This lets us fix strings and reuse them. To see why that is useful,
		: consider the following grammar
		:
		: Sentence -> Nounphrase Verbphrase   
		: Nounphrase -> Boy              
		: Nounphrase -> Girl           
		: Boy -> john
		: Boy -> ajit
		: Girl -> pima
		: Girl -> barkha
		: Verbphrase -> Verb Modlist Adverb with  Nounphrase
		: Verb -> runs                    
		: Verb -> walks                  
		: Modlist ->                    
		: Modlist -> very Modlist      
		: Adverb -> quickly           
		: Adverb -> slowly           
	    :
		: Note that now we can select two boys at different parts of the
		: story.
		:
		: But, in the following grammar, once we pick a heroine/ hero then we
		: always use their name (note the use of "=" in the following).
		:  
		: Sentence -> Nounphrase Verbphrase   
		: Nounphrase -> Boy              
		: Nounphrase -> Girl           
		: Boy = john
		: Boy = ajit
		: Girl = pima
		: Girl = barkha
		: Verbphrase -> Verb Modlist Adverb travels with  Nounphrase
		: Verb -> runs                    
		: Verb -> walks                  
		: Modlist ->                    
		: Modlist -> very Modlist      
		: Adverb -> quickly           
		: Adverb -> slowly    
           
	Note
		: Of course, the grammar still is "broken" since in this story,
		: the someone can travel with themselves.  
		: e.g. "pima runs slowly with pima" 
		: What we need is a better
		: constraint language in our grammar such that we can specify that
		: someone cannot travel with themselves. We will build such a grammar,
		: later in the semester.
	Test
		: Show that a grammar with the "=" sign can load and selections from
		: "=" rules remain constant.