Most people have had some experience with ruby’s built in #uniq method for Arrays. Internally, this method finds the unique items in the array by creating a hash internally, and this internal comparison is done with the #eql? method. If an item in the array is a Hash, then #eql? simply uses the object_id, generated by the #hash method, to determine whether it is equal to another object in the array. There are many solutions online each with s light variations and goals. I found myself in need of a uniq method for an array containing items in an arbitrarily deep nested structure (ie many sub-hashes and arrays). (more…)