From: Rick DeNatale <rick.denatale@...>
Date: 2008-03-19T19:45:52+09:00
Subject: Re: Undefined method '<' for nil:NilClasse

On 3/19/08, Roberto Casadei <robyonrails@katamail.com> wrote:
> This is the code:
>  class StringScanner
>   @str = ""
>   @kounter = 0

  Since the previous two lines are inside a class context rather than
inside an instance method, they define two class instance variables,
i.e. they are instance variables of the class object named
StringScanner.

These two variables are never actually used in the rest of the code,
much as it might seem to an untrained eye.

>   def initialize(str)
>     @str = str

   This creates an instance variable for the INSTANCE of StringScanner
being initialized, this is an entirely different variable than the
@str we saw before.
>   end
>   def scan(arg)
>     res = @str.scan(arg)
>     return nil unless @kounter<res.length

Again @kounter is an instance variable associated with a particular
StringScanner object, it is NOT the previously seen @kounter.

>     @kounter=@kounter+1
>     res[@kounter-1]
>   end
>  end
>
>  str = "Watch how I soar!"
>  ss = StringScanner.new(str)
>  loop do
>   word = ss.scan(/\w+/)    # Grab a word at a time
>   break if word.nil?
>   puts word
>   sep = ss.scan(/\W+/)     # Grab next non-word piece
>   break if sep.nil?
>  end
>

Now even if you straighten out the two variables, you are going around
Robin Hood's barn to accomplish what can be easily done with:

"Watch how I soar!".scan(/\w+/).each {|word| puts word}

or perhaps

  puts "Watch how I soar!".scan(/\w+/).join("\n")


-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/