From: "trans (Thomas Sawyer)" Date: 2012-08-13T08:06:56+09:00 Subject: [ruby-core:47141] [ruby-trunk - Feature #6847] Hash#extract Issue #6847 has been updated by trans (Thomas Sawyer). It important to understand the differences and to determine the best definition. ActiveSupport's #slice returns the same type of class, which I think is important, where as #extract! always returns a Hash. Also, #slice and #slice! are provided, where as there is only #extract! in ActiveSupport. Certainly we want both. ActiveSupport's #slice also has a special feature for #convert_key, which I think that would be nice for Ruby to have too, but it is not part of Ruby at this time. So that would obviously be omitted. I concur with Clay that #slice is the better name b/c Array#[] and Array#slice are pretty much the same, and though it might be a little bit more different that general relationship should also hold for Hash. ---------------------------------------- Feature #6847: Hash#extract https://bugs.ruby-lang.org/issues/6847#change-28802 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 -- http://bugs.ruby-lang.org/