Ruby 2 improved the support to keyword arguments. You can define your method with the default hash params as *args, and rid the options = {}. And no more need of options.reverse_merge(default_options).

def foo(bar: 'initial')
  puts bar
end

foo # => 'initial'
foo(bar: 'final') # => 'final'

Required arguments: you need a colon after the key (also you need ruby 2.1) 

def foo(bar:)
  puts bar
end

foo # => ArgumentError: missing keyword: bar
foo(bar: 'baz') # => 'baz'
foo(bar: nil) # => "\n"
              # don't show error, nil is a valid value for bar

Optional arguments: just set the default to nil

def foo(bar: nil, baz: 'aaa')
  puts "#{bar}:#{baz}"
end

foo # => ':aaa'
foo(baz: 'zab') # => ':zab'
foo(bar: 'rab', baz: 'zab') # => 'rab:zab'
foo(bin: 'bin') # => ArgumentError: unknown keyword: bin
foo(baz: nil) # => ':'

Also you can use the standard positional args with this new hash parameters notation. You will find more information at this blog and at the official documentation.

Bonus: The refactor is easy because you can rid the options hash of your method without changing it’s callers. But… this is not completely true, if you have a call with an unexpected option you will get an error: ArgumentError: unknown keyword: <the_invalid_arg>. And of course, calling with nil parameter is not the same of calling without it, you’ll lose the default value because nil is a valid one.