Programming Ruby

The Pragmatic Programmer's Guide

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class Symbol
Parent: Object
Version: 1.6


id2name inspect to_i to_s

A Symbol object represents a Ruby name and is generated automatically using the :name literal syntax. The same Symbol object will be created for a given name string for the duration of a program's execution, regardless of the context or meaning of that name. Thus if Fred is a constant in one context, a method in another, and a class in a third, the Symbol :Fred will be the same object in all three contexts.

module One
  class Fred
  $f1 = :Fred
module Two
  Fred = 1
  $f2 = :Fred
def Fred()
$f3 = :Fred
$ 2305294
$ 2305294
$ 2305294

instance methods
id2name sym.id2name -> aString

Returns the name corresponding to sym.

:fred.id2name "fred"

inspect sym.inspect -> aString

Returns the representation of sym as a symbol literal.

:fred.inspect ":fred"

to_i sym.to_i -> aFixnum

Returns an integer that is unique for each symbol within a particular execution of a program.

to_s sym.to_s -> aString

Synonym for Symbol#id2name .

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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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