如何覆盖哈希本机括号([]访问权限)

Question

我想覆盖ruby中的Hash类本机括号.

注意我不想在继承自Hash(没有子类化)的类中覆盖它们,我想实际上覆盖Hash本身,这样任何地方的任何哈希都将继承我的行为.

具体来说(奖励积分为......) - 我希望这能够本地模拟具有无差别访问权限的哈希.在JavaScript中我会修改prototype,Ruby以其元编程而闻名,所以我希望这是可能的.

所以我的目标是:

>> # what do I do here to overload Hash's []?...
>> x = {a:123} # x is a native Hash
>> x[:a] # == 123, as usual
>> x['a'] # == 123, hooray!

我试过了:1)

class Hash
  define_method(:[]) { |other| puts "Hi, "; puts other }
end

和

class Hash
  def []
    puts 'bar'
  end
end

两个都崩溃了.

Answer 1

这似乎完成了工作.

class Hash
  def [](key)
    value = (fetch key, nil) || (fetch key.to_s, nil) || (fetch key.to_sym, nil)     
  end

  def []=(key,val)
    if (key.is_a? String) || (key.is_a? Symbol) #clear if setting str/sym
        self.delete key.to_sym
        self.delete key.to_s        
    end
    merge!({key => val})
  end
end

现在:

user = {name: 'Joe', 'age' => 20} #literal hash with both symbols and strings as keys
user['name'] == 'Joe' # cool!
user[:age] == 20      # cool!

有关详细信息,请参阅:http://www.sellarafaeli.com/blog/ruby_monkeypatching_friendly_hashes