Misc #3401: arrays containing them selves do not apply == sensibly.

• Status: Rejected
• Assignee: -

[dmt10 (Dominic Tarr)]

=begin
a = [:a]
a << a
puts a
=> [:a [...]]

b = [:a]
b << b
puts b
=> [:a [...]]

#so , a == b?
puts a == b
=> false

#but they have the same structure...
puts a.to_yaml == b.to_yaml
=> true

#it looks like == compares the object_id's of arrays within arrays.
#more evidence:

c = [:a]
c << a
puts c
=> [:a, [:a, [...]]]
#clearly, a distinctly different array.
puts a == c
=> true
puts a.to_yaml == c.to_yaml
=> false

#this seems surprising behaviour to me
=end

[ujihisa (Tatsuhiro Ujihisa)]

=begin
FYI ruby 1.9 changed this behavior

 $ ruby193 -ve 'a=[:a];a<<a;b=[:a];b<<b;p a;p b;p a==b'
 ruby 1.9.3dev (2010-06-06 trunk 28190) [i386-darwin9.8.0]
 [:a, [...]]
 [:a, [...]]
 true

=end

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Rejected

=begin
Ruby 1.9's treatment of recursive structures has been set so that two structures are equal if they contain the elements that are equal, or said otherwise if no difference can be found between them. If you can give a "path" x, y, z..., such that a[x][y][z] != b[x][y][z], then and only then will a != b.

In your example, c[0] == a[0], c[1] == a[1] and c.size == a.size, so c == a.
=end