Accessing the last key–value pair in a Ruby (1.9) hash

As of Ruby 1.9, hashes retain ins开发者_如何学运维ertion order which is very cool. I want to know the best way to access the last key–value pair.

I've written some code which does this:

hash.values.last

This works and is very easy to comprehend, but perhaps it's possible to access the last value directly, rather that via an intermediary (the array of values). Is it?

---

Hash have a "first" method, but that return the first pair in array mode, for last, you can try:

my_hash.to_a.last

this return last pair in array mode like "first method"

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One more alternative that I'm using myself:

hash[hash.keys.last]

which works out better when you want to directly assign a value onto the last element of the hash:

2.4.1 :001 > hash = {foo: 'bar'}
 => {:foo=>"bar"} 
2.4.1 :002 > hash[hash.keys.last] = 'baz'
 => "baz" 
2.4.1 :003 > hash.values.last = 'bar'
NoMethodError: undefined method `last=' for ["baz"]:Array
Did you mean?  last
    from (irb):3
    from /home/schuylr/.rvm/rubies/ruby-2.4.1/bin/irb:11:in `<main>'

---

Nothing built in, no. But you could monkey-patch one if you were so inclined (not usually recommended, of course):

class Hash
  def last_value
    values.last
  end
end

And then:

hash.last_value

---

I just did this for a very large hash:

hash.reverse_each.with_index do |(_, value), index|
  break value if (index == 0)
end