hash_parameters.rb

require 'pp'

class Base

  def self.update_all(one, two = nil, three = {})
    puts "one:"
    pp one

    puts "two:"
    pp two

    puts "three:"
    pp three
  end

end

Base.update_all :foo => "foo", :bar => "bar"

puts

Base.update_all({ :foo => "foo" }, { :bar => "bar" })

# one:
# {:bar=>"bar", :foo=>"foo"}
# two:
# nil
# three:
# {}
# 
# one:
# {:foo=>"foo"}
# two:
# {:bar=>"bar"}
# three:
# {}