Issue #4541 has been updated by Gary Wright.


This discussion might help explain the rational for the current behavior: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/380636

There is also a related rationale in this posting: http://www.phwinfo.com/forum/comp-lang-ruby/462990-array-index-length-strange-behaviour.html#post2148794
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Bug #4541: Inconsistent Array.slice()
http://redmine.ruby-lang.org/issues/4541

Author: Marcin Pietraszek
Status: Assigned
Priority: Normal
Assignee: Yukihiro Matsumoto
Category: 
Target version: 1.9.3
ruby -v: ruby 1.9.2p136 (2010-12-25 revision 30365) [x86_64-linux]


=begin
Array slice/[] method is a bit inconsistent. Is it just poorly documented "feature" or a bug? In API doc I can't find this behaviour mentioned as a "special case".

 def test_array_slice
    array = ['a', 'b', 'c']
    assert_equal nil, array[3]
    assert_eaual nil, array[4]
 
    assert_eaual [], array[3, 0] #
    assert_equal nil, array[4, 0] # [] expected (or both nils in array[3, 0] and array[4, 0])
 
    assert_equal ['c'], array[2..2]
    assert_equal [], array[3..3] #
    assert_equal nil, array[4..4] # [] expected (or both nils in array[3..3] and array[4..4])
 end

Same behaviour can be reproduced on ruby 1.8.7 (2010-12-23 patchlevel 330) [x86_64-linux].
=end



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