A Taste of Ruby (Part 7)
Posted by Mark on September 3, 2008
This is a multi-part series. The first in the series is here.
Tower of Hanoi — Rules on Rails
In part 6 we changed the algorithm of Tower Of Hanoi to work without requiring the stack — it instead “more naturally” put sufficient state and logic into the model that the model could start and stop and continue as needed. I believe with Ruby 1.8.x, this is required to have Rails be able to work with the Tower of Hanoi. So we should try it out and see how well it works 
require 'hanoi_7'
class HanoiController < ApplicationController
def say
@hanoi = session[:hanoi]
if (@hanoi == nil) then
@hanoi = createHanoi
session[:count] = 0
session[:consoleLog] = ""
end
@hanoi.initApp(self)
@isDone = @hanoi.doNextMove_IsDone()
#clear the app because otherwise it will be part of the attempted serialization
#could also override the marshaling code, but this is simpler
@hanoi.initApp(nil)
#clear out the session variable, but @hanoi is still valid through
#the rest of this interaction
session[:hanoi] = @isDone ? nil : @hanoi
@count = session[:count] ||= 0
@count += 1
session[:count] = @count
if (@isDone) then
render(:action => 'say_done')
end
end
def appendLog(outString)
logger.info("Append to Log: "+outString)
@consoleLog = session[:consoleLog] ||= "\n"
@consoleLog = @consoleLog + outString + "\n"
session[:consoleLog] = @consoleLog
end
def noteChange
end
def createHanoi
hanoi = RulesTowerOfHanoi.new
hanoi.initHeight(5)
hanoi.setup_disks
return hanoi
end
def getAsciiTowers
result = ""
lines = Array.new
@hanoi.stacks.each_with_index do | eachStack, i |
0.upto(10) do | j |
eachDisk = eachStack[j]
if (eachDisk == nil) then
newLine = " "*12
else
newLine = eachDisk.to_s
end
newLine << " "*(12 - newLine.length)
currentLine = lines[j] ||= ""
lines[j] = currentLine+" "+newLine
end
end
lines.reverse.each {|line| result += line + "\n"}
return result
end
end
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Foo <%= @page_title %></title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="refresh" content="1">
<%= javascript_include_tag :defaults %>
</head>
<body<% if @page_class %> class="<%= @page_class %>"<% end %>>
<h1>Tower of Hanoi (Move <%= @count %>) </h1>
It's <%= Time.now %>.
<br/>
Done = <%= @isDone %>
<br/>
Render =
<pre>
<%= controller.getAsciiTowers %>
</pre>
Log =
<pre>
<%= @consoleLog %>
</pre>
</body>
