From: "trans (Thomas Sawyer)" <transfire@...>
Date: 2012-08-11T23:55:32+09:00
Subject: [ruby-core:47132] [ruby-trunk - Feature #6847] Hash#extract


Issue #6847 has been updated by trans (Thomas Sawyer).


Ruby Facets has Hash#slice as well.

  http://rdoc.info:8080/github/rubyworks/facets/master/Hash#slice-instance_method

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Feature #6847: Hash#extract
https://bugs.ruby-lang.org/issues/6847#change-28786

Author: citizen428 (Michael Kohl)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 


I often need a method to extract "subhashes" from hashes. I often monkey-patched this into hash and found "extract" to be a good name for the method. Afterwards I found out that there actually is a mutating method called "extract!" in ActiveSupport, so I guess the name is kinda established. Here's the Ruby version from my private extension library, if there's any interest in this I would try to re-implement it in C:

class Hash
  def extract(*ks)
    existing = keys & ks
    Hash[existing.zip(values_at(*existing))]
  end
end


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