From: pyarnau@...
Date: 2014-02-13T10:38:22+00:00
Subject: [ruby-core:60683] [ruby-trunk - Feature #666] Enumerable::to_hash

Issue #666 has been updated by Arnau Sanchez.


For those interested in this feature, check #7292, Marc-Andre implemented Array#to_h and Enumerable#to_h. It's not as powerful (since it takes no block, you'll usually need an intermediate array with "map"), but it's definitely better than Hash[pairs]. Thanks Marc-Andre.

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Feature #666: Enumerable::to_hash
https://bugs.ruby-lang.org/issues/666#change-45108

* Author: Marc-Andre Lafortune
* Status: Rejected
* Priority: Low
* Assignee: Yukihiro Matsumoto
* Category: 
* Target version: 2.0.0
----------------------------------------
=begin
 There are many ways to obtain an array from enumerables (to_a, map, ...).
 There is no natural way to obtain a hash from an enumerable (except for Hash[some_array]).
 There is a Hash::to_a but no Array::to_hash.
 Here is what I would like:
 
 [[:hello, "world"], [:choice, [:red_pill, :blue_pill]]].to_hash ==> {:hello=>"world", :choice=>[:red_pill, :blue_pill]}
 (1..3).to_hash{|n| [n, n**2]} ==> {1 => 1, 2 ==> 4, 3 ==> 9}
 
 I propose to add the following Enumerable::to_hash :
 
 module Enumerable
   def to_hash
     result = {}
     self.each do |key, value|
       key, value = yield(key, value) if block_given?
       result[key] = value
     end
     result
   end
 end
 
 Since Hash::to_a returns an array of key-value pairs, I fell it's natural that a block to construct a Hash should return key-value pairs. 
 This definition has nice symmetric properties: for any Hash h, the following all return a copy of h.
 h.to_a.to_hash
 h.to_hash{|p| p}
 h.to_hash{|k,v| [k,v]}
 h.keys.zip(h.values).to_hash
 
 Thank you for your attention,
 
 Marc-Andre Lafortune
=end




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