Issue #6367 has been updated by edtsech (Edward Tsech).


I don't know, but I was a little bit confused by that:
=begin
assert_equal(true, [1,3,9,7].same?(&:even?))
assert_equal(true, [4,8,2,2].same?(&:even?))
=end
or I can write smth like that:
=begin
assert_equal(true, [1.0,2.0,3.0,4.0].same?(&:integer?))
=end
Maybe it's just unusable for "primitive" types, 
because as i understand this method useful for test if all objects in enumerable have the same "property", 
and "primitive" types actually don't have them.

But I like this idea: 
=begin
assert_equal(true, %w{cat dog rat}.same?(&:length))
assert_equal(false, %w{cat dog rabbit}.same?(&:length))
=end
----------------------------------------
Feature #6367: #same? for Enumerable
https://bugs.ruby-lang.org/issues/6367#change-26282

Author: prijutme4ty (Ilya Vorontsov)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 


I realised that I frequently test if all objects in enumerable have the same feature. For example if all words have the same length (but not defined before). So I found particulary useful method Enumerable#same_by? that test this behaviour. I think it can be simply rewritten in C and included to Enumerable core methods.
Simple ruby implementation can be written just in a pair of lines (tests included):

module Enumerable
  def same?(&block)
    return true if empty?
    if block_given?
      first_result = yield(first)
      all?{|el| first_result == yield(el)}
    else
      first_result = first
      all?{|el| first_result == el}
    end
  end
end

require 'test/unit'
class TestEnumerableSame < Test::Unit::TestCase
  def test_same
    assert_equal(true, [1,3,9,7].same?(&:even?))
    assert_equal(true, [4,8,2,2].same?(&:even?))
    assert_equal(false, [1,8,3,2].same?(&:even?))
    
    assert_equal(true, %w{cat dog rat}.same?(&:length))
    assert_equal(false, %w{cat dog rabbit}.same?(&:length))
    
    assert_equal(true, %w{cat cat cat}.same?)
    assert_equal(false, %w{cat dog rat}.same?)
    
    assert_equal(true, [].same?(&:length))
    assert_equal(true, [].same?)
  end
end



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