From: Vladimir Sizikov <vsizikov@...>
Date: 2008-08-02T09:02:16+09:00
Subject: [ruby-core:18076] Equality of recursive arrays

Hi,

I'm currently writing RubySpecs for all Array methods with recursive
arrays, and I noticed something that I'd like to double-check with
you.

Essentially, the equality is not working right for recursive arrays,
at least it seems that it doesn't work right for me:

Case #1:

a = []
a << a
b = []
b << b

a == b #=> returns *false*

Is that expected or bug? The inspect values are the same.

On the other hand, when we use #dup:

Case #2:

a = [1]
a << a
b = a.dup

a == b #=> returns *true*

But if you look at the inspect values for a and b, you'll see:

a: [1, [...]]
b: [1, [1, [...]]]

This seems to be weird.

So, in the first case, the values seem to be equal, but #== returns
false for them, and
in the second case, the values seem to be different, but #== returns true. Huh?

Thanks,
  --Vladimir