From: Eric Mahurin <eric.mahurin@...>
Date: 2005-11-23T08:19:58+09:00
Subject: Re: a == nil or a.nil?

On 11/22/05, ako... <akonsu@gmail.com> wrote:
> hello,
>
> this is more of a philosophical question. my C experience makes me feel
> more comfortable with expressions such as 'a == nil' rather than
> a.nil?. i feel strange when i invoke a method on a nil value. i know,
> nil is also an object and not just a zero reference but still it feels
> strange...
>
> would the experts please comment on why one way would be preferable
> over the other? also, i am curious to know why nil? has been
> implemented at all? is '== nil' not enough?
>
> thanks
> konstantin

== is usually meant to query whether the data in the objects are the
same (or they are the same object).  For most == methods, if the data
is not comparable (not the same class), it will return false rather
than raise an exception.  So... == nil should work fine in most cases.

I would use one of these which are more direct:

a.nil?
nil==a    # uses the NilClass#== rather than an arbitrary ==
a.equal?(a)
nil.equal?(a)