# The ANIMAL game in Archetype.  A neat demo!  The ability to save total
# object state in Archetype is used to painlessly and transparently save
# the question/answer database.  Because of this, the initial database is
# stored directly within the code!  Showcases some unusual features
# of Archetype.
#
# Author:  DTJ  11/26/94

null main

  branch      : UNDEFINED
  alternative : UNDEFINED
  key_pressed : UNDEFINED
  response    : UNDEFINED

methods

  'AFFIRM' : {
    response := ( ((key_pressed := key) leftfrom 1) within "yY" )
    write key_pressed
    response
    }

  'START' : {
    writes "Load old game? "
    if 'AFFIRM' -> main then {
      writes "Name of file? "
      'LOAD STATE' -> system
      read -> system
    }
    while TRUE do {
      'PLAY'
      writes "Another game [y/n] ? "
      if not 'AFFIRM' -> main then {
        writes "Save this game? "
        if 'AFFIRM' -> main then {
          writes "Save to file: "
          'SAVE STATE' -> system
          read -> system
        }
        stop "Thanks for playing."
      }
    }
  }

  'PLAY' : {
    write "Think of an animal; hit any key when ready."; key
    branch := beginning
    while alternative := 'QUESTION' -> branch do
      branch := alternative
    write "You were thinking of... ", 'ANSWER' -> branch, "!"
    writes "Am I right? "
    if 'AFFIRM' -> main then
      write "I knew it!"
    else
      'EXTEND' -> branch
    }

end


type question based on null

  IfYes : UNDEFINED
  IfNo  : UNDEFINED
  Q     : UNDEFINED
  A     : UNDEFINED

methods

  'QUESTION' :
    if Q then {
      writes Q & " "
      if 'AFFIRM' -> main then IfYes else IfNo
    }

  'ANSWER'   : A
  'EXTEND'   : {
    create question named IfYes
    writes "What were you thinking of? "
    IfYes.A := read
    write "What question could I ask to distinguish \"", A, "\" from \"",
            IfYes.A, "\" ? "
    Q := read
    create question named IfNo
    IfNo.A := A
    writes "So if I ask \"", Q, "\", the right answer is \"", IfYes.A, "\" ? "
    if not 'AFFIRM' -> main then {
      A := IfNo.A
      IfNo.A := IfYes.A
      IfYes.A := A
    }
    A := UNDEFINED
  }

end


# To get things started:  one question with a yes and no answer

question beginning
  IfYes : whale
  IfNo  : dog
  Q     : "Does it live in the water?"
end
question whale          A : "a whale"       end
question dog            A : "a dog"         end