From: "Urabe Shyouhei" <shyouhei / ruby-lang.org>
> 
> FYI, expression "true" refers to the same object on multiple invocations:
> 
> irb(main):001:0> a = true
> => true
> irb(main):002:0> a.instance_variable_set "@foo", ["bar", "baz"]
> => ["bar", "baz"]
> irb(main):003:0> b = true
> => true
> irb(main):004:0> b.instance_variable_get "@foo"
> => ["bar", "baz"]
> irb(main):005:0>

Oh.  Forgot about that...  (I see it works with symbols, too.)

So they're not really immutable after all, and thus can't
be dup'd.

Interesting.


Regards,

Bill