From: Intransition <transfire@...>
Date: 2011-06-04T21:35:47+09:00
Subject: Re: Best way to replace hash keys



On Jun 3, 10:27 am, Alex Allmont <Alex.Allm...@naturalmotion.com>
wrote:
> What is the most optimal and neatest way to replace keys in a hash given a particular condition?
>
> I'm currently using delete_if and putting replacement values into a new hash before merging them back into the original hash.  Another approach would to simply rebuild a whole new hash.
>
>   # Contrived example: given searchReplacePairs hash of { search => replace } pairs,
>   # convert any String keys to a Regexp.
>   newPairs = { }
>   searchReplacePairs.delete_if do |search, replace|
>     if search.class == String
>       newPairs[Regexp.new(search)] = replace
>     end
>   end
>   searchReplacePairs.merge! newPairs

I'm not sure your example actually works, I think you'll end up with
both string AND regexp keys.

Here's an alternative:

  require 'facets/hash/rekey'

   searchReplacePairs.rekey! do |search, replace|
     search.class == String ? Regexp.new(search) : search
   end

See http://rubydoc.info/github/rubyworks/facets/master/Hash#rekey-instance_method

It's one of my favorite core extensions.