From: Michael Sung <lists@...>
Date: 2012-07-01T21:19:53+09:00
Subject: Question on Learning Ruby the Hard Way

Hi, I have a question on Exercise 43 of Learning Ruby the Hard Way.

Specifically, I'm wondering if someone to talk me through what's
happening below.

def play()
    next_room = @start

    while true
      puts "\n--------"
      room = method(next_room)
      next_room = room.call()
    end
  end


I can see that variable next_room is set to instance variable @start.
But how does this "while" loop work?  I'm also not familiar with how
"method" and "call" are both used here, as well as the : used in return
(e.g. return :central_corridor) below.



class Game

  def initialize(start)
    @quips = [
      "You died.  You kinda suck at this.",
      "Nice job, you died ...jackass.",
      "Such a luser.",
      "I have a small puppy that's better at this."
    ]
    @start = start
  end

  def prompt()
    print "> "
  end

def central_corridor()
    puts "The Gothons of Planet Percal #25 have invaded your ship and
destroyed"
    puts "your entire crew.  You are the last surviving member and your
last"
    puts "mission is to get the neutron destruct bomb from the Weapons
Armory,"
    puts "put it in the bridge, and blow the ship up after getting into
an "
    puts "escape pod."
    puts "\n"
    puts "You're running down the central corridor to the Weapons Armory
when"
    puts "a Gothon jumps out, red scaly skin, dark grimy teeth, and evil
clown costume"
    puts "flowing around his hate filled body.  He's blocking the door
to the"
    puts "Armory and about to pull a weapon to blast you."

    prompt()
    action = gets.chomp()

    if action == "shoot!"
      puts "Quick on the draw you yank out your blaster and fire it at
the Gothon."
      puts "His clown costume is flowing and moving around his body,
which throws"
      puts "off your aim.  Your laser hits his costume but misses him
entirely.  This"
      puts "completely ruins his new costume his mother bought
him, which"
      puts "makes him fly into an insane rage and blast you repeatedly
in the face until"
      puts "you are dead.  Then he eats you."
      return :death

    elsif action == "dodge!"
      puts "Like a world class boxer you dodge, weave, slip and slide
right"
      puts "as the Gothon's blaster cranks a laser past your head."
      puts "In the middle of your artful dodge your foot slips and you"
      puts "bang your head on the metal wall and pass out."
      puts "You wake up shortly after only to die as the Gothon stomps
on"
      puts "your head and eats you."
      return :death

    elsif action == "tell a joke"
      puts "Lucky for you they made you learn Gothon insults in the
academy."
      puts "You tell the one Gothon joke you know:"
      puts "Lbhe zbgure vf fb sng, jura fur fvgf nebhaq gur ubhfr, fur
fvgf nebhaq gur ubhfr."
      puts "The Gothon stops, tries not to laugh, then busts out
laughing and can't move."
      puts "While he's laughing you run up and shoot him square in the
head"
      puts "putting him down, then jump through the Weapon Armory door."
      return :laser_weapon_armory

    else
      puts "DOES NOT COMPUTE!"
      return :central_corridor
    end
  end

  def play()
    next_room = @start

    while true
      puts "\n--------"
      room = method(next_room)
      next_room = room.call()
    end
  end

a_game = Game.new(:central_corridor)
a_game.play()

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