Programming Ruby

The Pragmatic Programmer's Guide

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class Method
Parent: Object
Version: 1.6

Index:

[ ] 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)
    n*n
  end
end
aThing  = Thing.new
aMethod = aThing.method("square")
aMethod.call(9) 81
[ 1, 2, 3 ].collect(&aMethod) [1, 4, 9]

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

Synonym for Method.call.

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 meth.call( [ args ]* ) -> anObject

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

m = 12.method("+")
m.call(3) 15
m.call(20) 32

to_proc meth.to_proc -> aProc

Returns a Proc object corresponding to this method.


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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 http://www.opencontent.org/openpub/)).

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