hash.rb

class Hash
  def as_object
    HashObject.new self
  end
end

#> o = { foo: (->(this) { puts this.bar }), bar: 'hello') }.as_object
#> o.foo
# => hello

hash_object.rb

class HashObject
  def initialize hash = {}
    @hash = hash
  end

  def method_missing method, *args, &block
    _, key, is_setter = /(\w+)(=)$/.match(method.to_s).to_a
    result = @hash.has_key?(method) ? @hash[method] : @hash.default
    return (@hash[key] = args.first) if is_setter
    return result.is_a?(Proc) ? result[self, *args] : result
  end
end

#> o = HashObject.new(foo: (->(this) { puts this.bar }), bar: 'hello')
#> o.foo
# => hello