"clone" at active_record relation

andersonleite · September 6, 2010, 8:42pm

inside Rails source, at

rails/rails/blob/main/activerecord/lib/active_record/relation/query_methods.rb

# frozen_string_literal: true

require "active_record/relation/from_clause"
require "active_record/relation/query_attribute"
require "active_record/relation/where_clause"
require "active_support/core_ext/array/wrap"

module ActiveRecord
  module QueryMethods
    include ActiveModel::ForbiddenAttributesProtection

    # +WhereChain+ objects act as placeholder for queries in which +where+ does not have any parameter.
    # In this case, +where+ can be chained to return a new relation.
    class WhereChain
      def initialize(scope) # :nodoc:
        @scope = scope
      end

      # Returns a new relation expressing WHERE + NOT condition according to
      # the conditions in the arguments.

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I found a lot of calls to:

relation = clone

I can understand where id the “relation” call, but… how about “clone”
?
Perhaps “clone” comes from Ruby1.9-Kernel, but I am not sure.
And github color it in blue, like a class…weird…

def where(opts, *rest)
  relation = clone

  if opts.present? && value = build_where(opts, rest)
    relation.where_values += Array.wrap(value)
  end

  relation
end

Can somebody explain this “clone” ? Where it come from ?
Thanks