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by Hans Fugal
I am amazed whenever I see or hear about the rising generation of keypad
punchers. People that can carry on IM conversations with a 12-key phone
pad without instantly going mad; it's mind-boggling. As adaptive as the
rising generation is, the "Multitap" solution is far from efficient. For
example, I learned from Wheel of Fortune that the most common letters
are RSTLNE, only one of which (T) is the first tap on one of the keys.
Your mission then, should you choose to accept it, is to develop a more
efficient algorithm for key entry. User interaction is simply the 12
keys (0-9, * and #) with the letters printed on them as usual[1], and
visual feedback of what they have typed so far. Simulating algorithms
thought up by other people (e.g. LetterWise[2]) is fair game.
[ Editor's Note:
Hans sent the following code to get people started with a simple testing
inteface for their algorithms:
class TapEvent
attr_reader :when, :digit
def initialize(digit)
@digit = digit
@when = Time.now
end
def to_s
@digit
end
end
class PhonePad
attr_reader :text, :cursor
def set_text(text,cursor)
@text = text
@cursor = cursor
end
def register(&block)
@observers.push block
end
def initialize
@observers = []
@text = ''
@cursor = 0
end
def notify_observers(digit)
if digit =~ /[0-9*#]/
@observers.each { |block| block.call(TapEvent.new(digit)) }
end
end
end
class CLIPhonePad < PhonePad
def initialize
super
Thread.new do
while not $stdin.eof? do
$stdin.readline.split('').each { |c| notify_observers(c) }
end
end
end
def set_text(text,cursor)
super(text,cursor)
puts to_s
end
def run
end
def to_s
@text.dup.insert(@cursor,'_')
end
end
if $0 == __FILE__
p = CLIPhonePad.new
p.register do |ev|
puts "#{ev} at #{ev.when}"
p.set_text(p.text+ev.digit, p.cursor+1)
end
Thread.list[0].join
end
Hans's code is well suited to GUI adaption, if you're so inclined. (Please post
to Ruby Talk if you do build a GUI for this. That's not a spoiler.)
Here's another version by me, that doesn't require you press return after the
digits:
begin
require "Win32API"
def read_char
Win32API.new("crtdll", "_getch", [], "L").Call
end
rescue LoadError
def read_char
system "stty raw -echo"
STDIN.getc
ensure
system "stty -raw echo"
end
end
loop do
char = read_char.chr
case char
when /^(?:\d|\*|#)$/
### Replace the following line with your algorithm. ###
puts "You entered #{char}."
when /q/i
break
else
puts "'#{char}' is not a key on the keypad."
end
end
-JEG2 ]
This is an area of serious research for some people[2]; don't fret it if
your algorithm isn't perfect or ideal, and don't spend too long on it. 
Make your goal to be better than dumb, which is to say be better
than "Multitap".
1. http://www.yorku.ca/mack/uist01-f1.jpg
2. http://www.yorku.ca/mack/uist01.html
Still just a II, not a III. For the curious, I shorten my name as JEG2. Use whatever you like though, I answer to anything.