I've made a Ruby linked list data structure class and a lookup method. I know that lookup will only fetch the first occurrence and I'm ok with that.

Is it a bad implementation? Why is it bad? What can I improve to make it more idiomatic?

# linear collection of data elements, in which linear order is not given by
# their physical placement in memory. Instead, each element points to the next.
class LinkedList
  attr_accessor :value, :next

  def lookup(lookup_value)
    return self if value.eql? lookup_value
    return self.next.lookup(lookup_value) unless self.next.nil?

Test code

root = LinkedList.new
root.value = 5

node1 = LinkedList.new
node1.value = 10

node2 = LinkedList.new
node2.value = 15

node3 = LinkedList.new
node3.value = 12

root.next = node1
node1.next = node2
node2.next = node3

p root.lookup(2) # nil
p root.lookup(15) # #<LinkedList:0x007f83db0a95b8 @value=15, @next=#<LinkedList:0x007f83db0a9590 @value=12>>
p root.lookup(12) # #<LinkedList:0x007fcbe91196a0 @value=12>
  • 1
    \$\begingroup\$ I would certainly make it easier to add elements (say node.addNew(value) and create some sort of constructor maybe following the pattern used by Hash[], i..e root = LinkedList[values, ...] \$\endgroup\$ – Marc Rohloff Dec 4 '17 at 18:32

Looks pretty good to me. You don't need the explicit return as the last statement of your lookup method. Also, in newer versions of Ruby (2.3+ I believe), you don't need the explicit nil check--instead, you can use the Safe Navigation Operator (&.).

  def lookup(lookup_value)
    return self if value.eql? lookup_value

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