Screwing around with a CallableHash class in Ruby

CallableHash.rb

class CallableHash < Hash
  def initialize(h)
    h.each do |k, v|
      self[k] = v
    end
    @@methods = {}
  end

  def respond_to?(sym)
    true
  end

  def method_missing(sym, *args, &block)
    proc = @@methods[sym]
    if ! proc
      name = sym.to_s
      if string_ends_with?(name, '=')
        key = name[0..-2]
        proc = Proc.new {|v| self[key.to_sym] = v}
      else
        proc = Proc.new {self[sym]}
      end
    end
    proc.call(*args)
  end

  def get_binding
    binding()
  end

  private

  def string_ends_with?(s, sub)
    tail = s[-sub.length, sub.length]
    tail == sub
  end
end

h = CallableHash.new(:a => 1, :b => 2)
puts(h.inspect) # {:a=>1, :b=>2}
puts(h[:a])     # 1
h[:a] = 2 
puts(h[:a])     # 2
puts(h.a)       # 2
h.a = 3 
puts(h.a)       # 3
puts(h["a"])    # nil
h['a'] = 10
puts(h["a"])    # 10
puts(h.inspect) # {"a"=>10, :a=>3, :b=>2}
h.delete(:a)
puts(h[:a])     # nil
puts(h.a)       # nil
h.a = 'foo'
puts(h.inspect) # {"a"=>10, :b=>2, :a=>"foo"}
puts(h.a)       # foo