Issue #7793 has been updated by nobu (Nobuyoshi Nakada).


Considering existing methods:

  $ ruby -e 'p Hash.instance_methods(false).grep(/each_/)'
  [:each_value, :each_key, :each_pair]

They should be map_key, may_value, and map_pair, respectively, I
think.

Anyway, why don't you make it a gem first?

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Feature #7793: New methods on Hash
https://bugs.ruby-lang.org/issues/7793#change-35955

Author: dsisnero (Dominic Sisneros)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: 


It would be nice to have the following methods added to hash

h = { name: 'dominic', request: 'add the following methods', :why => 'convenience'}

h.map_v{|v| v.upcase} 
   {:name=>"DOMINIC", :request=>"ADD THE FOLLOWING METHODS", :why=>"CONVENIENCE"}

h.map_k{|k| k.to_s}
   { "name"=> 'dominic', "request"=>"add the following methods', "why" => "convenience"}

h.map_kv{|k,v| [k.to_s, v.upcase]}
   { "name"=>"DOMINIC", "request"=>"ADD THE FOLLOWING METHODS", "why"=>"CONVENIENCE"}


class Hash

  def map_v
    reduce({}) do |result, array|
      k,v = array
      new_val = yield v
      result.merge( k => new_val)
    end
  end

  def map_k
    reduce({}) do |result, array|
      k,v = array
      new_k = yield k
      result.merge(new_k => v)
    end
  end

  def map_kv
    reduce({}) do |result, array|
      new_k,new_v = yield array
      result.merge(new_k => new_v)
    end
  end

end


-- 
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