From: "marcandre (Marc-Andre Lafortune)" <ruby-core@...>
Date: 2012-11-26T15:23:34+09:00
Subject: [ruby-core:50149] [ruby-trunk - Bug #7437] Array#delete(obj) should return obj when there is an object that is equal in the array


Issue #7437 has been updated by marcandre (Marc-Andre Lafortune).

Category set to core
Target version set to 2.0.0

Indeed, the documentation does not match the code and there is no test for this.

It was clearly Matz' intention to return the (last) deleted element: https://bugs.ruby-lang.org/projects/ruby-trunk/repository/revisions/18527

This is the most helpful behavior anyways.

I'll note that the documentation is clearly wrong in the second form too.

Unless there is objection, I'll commit the following patch:

diff --git a/array.c b/array.c
index df0a0a4..481eebc 100644
--- a/array.c
+++ b/array.c
@@ -2605,12 +2605,12 @@ rb_ary_keep_if(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.delete(obj)            -> obj or nil
- *     ary.delete(obj) { block }  -> obj or nil
+ *     ary.delete(obj)            -> element or nil
+ *     ary.delete(obj) { block }  -> element or result of block
  *
  *  Deletes all items from +self+ that are equal to +obj+.
  *
- *  If any items are found, returns +obj+, otherwise +nil+ is returned instead.
+ *  Returns the last deleted item, or +nil+ if no matching item is found.
  *
  *  If the optional code block is given, the result of the block is returned if
  *  the item is not found.  (To remove +nil+ elements and get an informative
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index 8d264d9..6466fc3 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -598,6 +598,14 @@ class TestArray < Test::Unit::TestCase
     a = @cls[*('cab'..'cat').to_a]
     assert_equal(99, a.delete('cup') { 99 } )
     assert_equal(@cls[*('cab'..'cat').to_a], a)
+
+    o = Object.new
+    def o.==(other); true; end
+    o2 = Object.new
+    def o2.==(other); true; end
+    a = @cls[1, o, o2, 2]
+    assert_equal(o2, a.delete(42))
+    assert_equal([1, 2], a)
   end
 
   def test_delete_at


----------------------------------------
Bug #7437: Array#delete(obj) should return obj when there is an object that is equal in the array
https://bugs.ruby-lang.org/issues/7437#change-33938

Author: hasari (Hiro Asari)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0
ruby -v: ruby 2.0.0dev (2012-11-25 trunk 37839) [x86_64-darwin12.2.1]


According to http://www.ruby-doc.org/core-1.9.3/Array.html#method-i-delete, Array#delete(obj) should return "obj" when there are objects in the array that are "equal to obj" (internally, "==" is used, it seems).

Notice that the documentation does not state that the return value is an element of the array itself. However, 1.9.3 and trunk both return a member of the Array, rather than the argument.

This issue was raised in https://github.com/jruby/jruby/issues/411

#!/usr/bin/env ruby

class Foo
  attr_reader :name, :age

  def initialize name, age
    @name = name
    @age = age
  end

  def == other
    other.name == name
  end
end

foo1 = Foo.new "John Shahid", 27
foo2 = Foo.new "John Shahid", 28
array = [foo1]
temp = array.delete foo2 # => foo1, not foo2


-- 
http://bugs.ruby-lang.org/