gistfile1.rb

class Options < Hash
  def self.new(&a)
    a = lambda{|h,k| h[k] = new(&a) } unless a
    super(&a)
  end
  def method_missing(m, *a)
    if m[-1] == "="
      key = keys.find{|k| k.to_s == m[0...-1].to_s } || m[0...-1].to_sym
      self[key] = a.first
    else
      key = keys.find{|k| k.to_s == m.to_s }
      self[key]
    end
  end
end

h = Options.new
h[:a][:b][:c] = :foo
h[:d] = :bar

p h
p h.a
p h.a.b.c

h.e.f = :baz
p h.e