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, "<dankogai at dan.co.jp>"
BUGS
Please report any bugs or feature requests to "bug-tie-array-lazy at
rt.cpan.org", or through the web interface at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Tie-Array-Lazy>. 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
<
http://annocpan.org/dist/Tie-Array-Lazy>
* CPAN Ratings
<
http://cpanratings.perl.org/d/Tie-Array-Lazy>
* RT: CPAN's request tracker
<
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Tie-Array-Lazy>
* Search CPAN
<
http://search.cpan.org/dist/Tie-Array-Lazy>
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.
