Programming Ruby

The Pragmatic Programmer's Guide

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class TrueClass
Parent: Object
Version: 1.6


& ^ |

The global value true is the only instance of class TrueClass and represents a logically true value in boolean expressions. The class provides operators allowing true to be used in logical expressions.

instance methods
& true & anObject -> anObject

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

^ true ^ anObject -> !anObject

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

| true | anObject -> true

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

true |  puts("or")
true || puts("logical or")

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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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