NAME Tie::Array::Lazy - Lazy -- but mutable -- arrays. VERSION $Id: README,v 0.1 2007/05/26 17:55:24 dankogai Exp $ SYNOPSIS use Tie::Array::Lazy; # 0..Inf tie my @a, 'Tie::Array::Lazy', [], sub{ $_[0]->index }; print @a[0..9]; # 0123456789 $a[1] = 'one'; print @a[0..9]; # 0one23456789 print "$_\n" for @a; # prints forever DESCRIPTION Tie::Array::Lazy implements a *lazy array*, an array that generates the element on demand. It is a lot like a *lazy list* but unlike lazy lists seen in many functional languages like Haskell, lazy arrays are mutable so you can assign values to their elements. The example below explains how it works. tie my @a, 'Tie::Array::Lazy', [3,2,1,0], sub{ 1 }; my @r = splice @a, 1, 2, qw/two one/ # @r is (2,1); tied(@a)->array is [3,'two','one',0]; pop @a; # 0; tied(@a)->array is [3,'two','one']; shift @a; # 3; tied(@a)->array is ['two','one']; shift @a; # 'two'; tied(@a)->array is ['one']; pop @a; # 'one; tied(@a)->array is []; pop @a; # 1; tied(@a)->array is []; @a[3] = 3 # tied(@a)->array is [1,1,1,3]; You can think *lazy arrays* as arrays that auto-fills. EXPORT None. FUNCTIONS tie @array, 'Tie::Array::Lazy', *arrayref*, *coderef* makes @array a lazy array with its initial state with *arrayref* and element generator code with *coderef*. Here is an exmaple; The *coderef* is a code reference which $_[0] is the Tie::Array::Lazy object itself (tied(@array)) and $_[1] is the index. In addition to methods that Tie::Array provides, the object has methods below: array The reference to the internal array which stores values either generated or assigned. # Fibonacci array tie my @a, 'Tie::Array::Lazy', [1, 1], sub{ $_[0]->array->[-2] + $_[0]->array->[-1] } index Shorthand for "scalar @{ $self->array }". # 0..Inf tie my @a, 'Tie::Array::Lazy', [], sub{ $_[0]->index }; maker The reference to the code reference to generate the value needed. Whenever the value is needed, Tie::Array::Lazy invokes the code below; $self->maker($self, $index); Using Tie::Array::Lazy as a base class Like Tie::Array, you can use this module as a base class. See Tie::Array::Lazier for details. AUTHOR Dan Kogai, "" BUGS Please report any bugs or feature requests to "bug-tie-array-lazy at rt.cpan.org", or through the web interface at . I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. SUPPORT You can find documentation for this module with the perldoc command. perldoc Tie::Array::Lazy You can also look for information at: * AnnoCPAN: Annotated CPAN documentation * CPAN Ratings * RT: CPAN's request tracker * Search CPAN ACKNOWLEDGEMENTS Nick Ing-Simmons for Tie::Array Matsumoto Yukihiro (Matz) for teasing me into hacking this module. COPYRIGHT & LICENSE Copyright 2007 Dan Kogai, all rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.