任何人都可以弄清楚这块红宝石代码的作用是什么？

Question

Had this as part of an interview,I guessed it took incoming data, translated it into local language then commits to database? Which was obviously wrong.

def optimize(hsh)
  hsh.reduce({}) do |new_hsh, (k,v)|
    new_hsh[k.to_sym] = v.kind_of?(Hash) ? optimize(v) : v
    new_hsh
  end
end

Answer 1

It looks like it just recursively converts keys from nested hashes to symbols.

optimize({'k' => {'l' => 'v'}})
#=> {:k=>{:l=>"v"}}

Optimize is a poor name and each_with_object should be used instead of reduce :

def symbolize_keys(hash)
  hash.each_with_object({}) do |(k, v), new_hash|
    new_hash[k.to_sym] = v.is_a?(Hash) ? symbolize_keys(v) : v
  end
end

puts symbolize_keys('k' => { 'l' => 'v' })
#=> {:k=>{:l=>"v"}}

This method could be used to make sure that a nested hash has the correct keys. Some devs like to use string keys, others prefer symbols :

{'a' => 'b'}[:a]
#=> nil
symbolize_keys({'a' => 'b'})[:a]
#=> 'b'

Servers talk to each others with strings but Rails code is often written with symbols as keys. That's one of the reasons why HashWithIndifferentAccess exists.