Attribute::Constant - Make read-only variables via attribute
$Id: Constant.pm,v 0.6 2013/03/20 22:37:04 dankogai Exp dankogai $
use Attribute::Constant; my $sv : Constant( $initial_value ); my @av : Constant( @values ); my %hv : Constant( key => value, key => value, ...);
This module uses Data::Lock to make the variable read-only. Check the document and source of Data::Lock for its mechanism.
This module adds only one attribute, Constant. You give its initial value as shown. Unlike Readonly, parantheses cannot be ommited but it is semantically more elegant and thanks to Data::Lock, it imposes almost no performance penalty.
Constant
Multi-line attributes are not allowed in Perl 5.8.x.
my $o : Constant(Foo->new(one=>1,two=>2,three=>3)); # ok my $p : Constant(Bar->new( one =>1, two =>2, three =>3 ) ); # needs Perl 5.10
In which case you can use Data::Lock instead:
dlock(my $p = Bar->new( one => 1, two => 2, three => 3 ) );
After all, this module is a wrapper to Data::Lock;
Here I have benchmarked like this.
1. Create an immutable variable. 2. try to change it and see if it raises exception 3. make sure the value stored remains unchanged.
See t/benchmark.pl for details.
Rate Readonly glob Attribute Readonly 7803/s -- -97% -97% glob 281666/s 3510% -- -5% Attribute 295780/s 3691% 5% --
Rate Readonly Attribute Readonly 8589/s -- -97% Attribute 278755/s 3145% --
Rate Readonly Attribute Readonly 6979/s -- -97% Attribute 207526/s 2874%
Data::Lock, constant
Dan Kogai, <dankogai+cpan at gmail.com>
<dankogai+cpan at gmail.com>
Please report any bugs or feature requests to bug-attribute-constant at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Attribute-Constant. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
bug-attribute-constant at rt.cpan.org
You can find documentation for this module with the perldoc command.
perldoc Attribute::Constant
You can also look for information at:
RT: CPAN's request tracker
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Attribute-Constant
AnnoCPAN: Annotated CPAN documentation
http://annocpan.org/dist/Attribute-Constant
CPAN Ratings
http://cpanratings.perl.org/d/Attribute-Constant
Search CPAN
http://search.cpan.org/dist/Attribute-Constant
Readonly
Copyright 2008 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.
To install Attribute::Constant, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Attribute::Constant
CPAN shell
perl -MCPAN -e shell install Attribute::Constant
For more information on module installation, please visit the detailed CPAN module installation guide.