Programming Ruby

The Pragmatic Programmer's Guide

Previous < Contents ^
Next >
class Method
Parent: Object
Version: 1.6


[ ] arity call to_proc

Method objects are created by Object#method , and are associated with a particular object (not just with a class). They may be used to invoke the method within the object, and as a block associated with an iterator.

class Thing
  def square(n)
aThing  =
aMethod = aThing.method("square") 81
[ 1, 2, 3 ].collect(&aMethod) [1, 4, 9]

instance methods
[ ] meth[ [ args ]* ] -> anObject

Synonym for

arity meth.arity -> aFixnum

Returns an indication of the number of arguments accepted by a method. Returns a nonnegative integer for methods that take a fixed number of arguments. For Ruby methods that take a variable number of arguments, returns -n-1, where n is the number of required arguments. For methods written in C, returns -1 if the call takes a variable number of arguments.

call [ args ]* ) -> anObject

Invokes the meth with the specified arguments, returning the method's return value.

m = 12.method("+") 15 32

to_proc meth.to_proc -> aProc

Returns a Proc object corresponding to this method.

Previous < Contents ^
Next >

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

Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder.

Distribution of the work or derivative of the work in any standard (paper) book form is prohibited unless prior permission is obtained from the copyright holder.