From: Xavier Noria <fxn@...>
Date: 2010-02-25T07:37:10+09:00
Subject: Re: Iterate over hash of nested hashes

On Wed, Feb 24, 2010 at 11:17 PM, Glenn Ritz <glenn_ritz@yahoo.com> wrote:
> Xavier Noria wrote:
>> On Wed, Feb 24, 2010 at 10:40 PM, Glenn Ritz <glenn_ritz@yahoo.com>
>> wrote:
>>
>>> I'd like to be able to take a hash whose values are either hashes or
>>> some other object. If the values are hashes, I'd like to iterate over
>>> them and keep this up until the values aren't hashes.  And I won't know
>>> how many level there will be until the program is running.  Any
>>> suggestions?
>>
>> The iterator should yield... what? key, value pairs when it gets to a
>> leave? Only values? All pairs no matter the type of the value?
>
> If the Hash looks like this:
>
> {'en' => {'A' => 1, 'B' => {'C' => 3, 'D' => 'four' }}
>
> I'd like to be able to create a new hash that looks like this (it's for
> a gem that I am trying to write):
>
> {'en' => {'A' => Fixnum, 'B' => {'C' => Fixnum, 'D' => String }}
>
> So I think it should yield the key value pairs when it gets to a leaf,
> but it also seems like I will need more to be able to create the above
> hash.

For example

def classify_values(h)
  newh = {}
  h.each do |k, v|
    newh[k] = v.is_a?(Hash) ? classify_values(v) : v.class
  end
  newh
end

p classify_values({'en' => {'A' => 1, 'B' => {'C' => 3, 'D' => 'four' }}})

I'd use Active Support's #returning if available.