Programming Ruby

The Pragmatic Programmer's Guide

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class NilClass
Parent: Object
Version: 1.6


& ^ | nil? to_a to_i to_s

The class of the singleton object nil.

instance methods
& nil& anObject -> false

And---Returns false. As anObject is an argument to a method call, it is always evaluated; there is no short-circuit evaluation in this case.

nil && puts("logical and")
nil &  puts("and")

^ nil^ anObject -> true or false

Exclusive Or---Returns false if anObject is nil or false, true otherwise.

| nil| anObject -> true or false

Or---Returns false if anObject is nil or false, true otherwise.

nil? nil.nil? -> true

Always returns true.

to_a nil.to_a -> []

Always returns an empty array.

to_i nil.to_i -> 0

Always returns zero.

to_s nil.to_s -> ""

Always returns the empty string.

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Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at

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