From: Seth Eliot <seth_ruby@...>
Date: 2006-10-23T07:51:00+09:00
Subject: Ruby-ize me (or at least my code)

Hi all,

I am new to Ruby but find it interesting.  To teach myself the language 
I wrote a simple linked list implementation.  It works just fine, but I 
suspect that my "Java is showing" and that the same logic can be written 
in a much more Ruby-ish fashion.

So I'd appreciate it if you can show me the Ruby way of implementing the 
following functionality.

(The one thing I know is that I am not really taking advantage of OOP by 
making my methods in LinkedListSe.rb just static utility methods… that's 
fine for now)
(also "next_1" is just my way of not colliding with the reserved keyword 
"next")

File: ElemLL.rb

class ElemLL

  attr_accessor :data, :next_1

  @data
  @next_1
End

File: LinkedListSe.rb

require 'ElemLL'

# Adds element to end of linked list
def addData(data, head=nil)
    insertData(data, head)
end

# Inserts Element at requested index in linked list.
# Shifts the element currently at that position (if any) and any 
subsequent
# elements to the right (adds one to their indices)
def insertData(data, head, index=nil)

    # special case if list currently empty (not initialized)
    return newList(data) unless head

    # Weakly typed languages have their downsides? :-)
    return unless head.class == ElemLL

    # Initial values for first element
    i = 1
    prev = nil
    curr = head
    next_1 = curr.next_1

    # Iterate through elements until we reach insertion point (or end of 
list)
    while (curr && (!index || i<index))
        prev=curr
        curr = next_1;
        next_1 = curr.next_1 if curr;
        i=i.next
    end

    # when new element is inserted, the current curr will actually be 
next
    next_1 = curr

    # Create the new element at curr
    curr = ElemLL.new
    curr.data = data
    curr.next_1=next_1

    # Set the pointer *to* the new element
    if (prev)
        prev.next_1 = curr
    else
        head=curr
    end

    return head
end

def traverse(head)
    puts "\nLinked List contents:"

    curr = head
    while(curr)
        puts "   #{curr.data}"
        curr = curr.next_1
    end
end

def newList(data)
    head = ElemLL.new
    head.data = data
    return head
end

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