[ruby-core:65509] [ruby-trunk - Feature #7793] New methods on Hash

Issue #7793 has been updated by Tsuyoshi Sawada.


Just like there are `map` and `map!`, there should be both a non-desctructive and a destructive version for this method.

~~~ruby
h = {a: "foo"}

h.non_destructive_one{|k, v| [k.to_s, v.upcase]} #=> {"a" => "FOO"}
h #=> {a: "foo"}

h.destructive_one!{|k, v| [k.to_s, v.upcase]} #=> {"a" => "FOO"}
h #=> {"a" => "FOO"}
~~~

I also have a (not that strong) opinion that the block for these methods should take a hash rather than an array. That should make more sense since the return value is a hash.

~~~ruby
h.non_destructive_one{|k, v| {k.to_s => v.upcase}} #=> {"a" => "FOO"}
h.destructive_one!{|k, v| {k.to_s => v.upcase}} #=> {"a" => "FOO"}
~~~

----------------------------------------
Feature #7793: New methods on Hash
https://bugs.ruby-lang.org/issues/7793#change-49284

* Author: Dominic Sisneros
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: core
* Target version: next minor
----------------------------------------
It would be nice to have the following methods added to hash

~~~ruby
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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