NAME

Data::Lock - makes variables (im)?mutable

VERSION

$Id: Lock.pm,v 1.3 2014/03/07 18:24:43 dankogai Exp dankogai $

SYNOPSIS

   use Data::Lock qw/dlock dunlock/;

   dlock my $sv = $initial_value;
   dlock my $ar = [@values];
   dlock my $hr = { key => value, key => value, ... };
   dunlock $sv;
   dunlock $ar; dunlock \@av;
   dunlock $hr; dunlock \%hv;

DESCRIPTION

"dlock" makes the specified variable immutable like Readonly. Unlike Readonly which implements immutability via "tie", "dlock" makes use of the internal flag of perl SV so it imposes almost no penalty.

Like Readonly, "dlock" locks not only the variable itself but also elements therein.

As of verion 0.03, you can "dlock" objects as well. Below is an example constructor that returns an immutable object:

  sub new {
      my $pkg = shift;
      my $self = { @_ };
      bless $self, $pkg;
      dlock($self);
      $self;
  }

Or consider using Moose.

EXPORT

Like List::Util and Scalar::Util, functions are exported only explicitly. This module comes with "dlock" and "dunlock".

  use Data::Lock;                   # nothing imported;
  use Data::Lock qw/dlock dunlock/; # imports dlock() and dunlock()

FUNCTIONS

dlock

  dlock($scalar);

Locks $scalar and if $scalar is a reference, recursively locks referents.

dunlock

Does the opposite of "dlock".

BENCHMARK

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.

Simple scalar

                Rate  Readonly Attribute      glob     dlock
  Readonly   11987/s        --      -98%      -98%      -98%
  Attribute 484562/s     3943%        --       -1%       -4%
  glob      487239/s     3965%        1%        --       -3%
  dlock     504247/s     4107%        4%        3%        --

Array with 1000 entries

                Rate  Readonly     dlock Attribute
  Readonly   12396/s        --      -97%      -97%
  dlock     444703/s     3488%        --       -6%
  Attribute 475557/s     3736%        7%        --

Hash with 1000 key/value pairs

                Rate  Readonly     dlock Attribute
  Readonly   10855/s        --      -97%      -97%
  dlock     358867/s     3206%        --       -5%
  Attribute 377087/s     3374%        5%        --

AUTHOR

Dan Kogai, "<dankogai+gmail at gmail.com>"

BUGS

Please report any bugs or feature requests to "bug-data-lock at rt.cpan.org", or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Data-Lock>. 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 Data::Lock

You can also look for information at:

RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Data-Lock>
AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/Data-Lock>
CPAN Ratings
<http://cpanratings.perl.org/d/Data-Lock>
Search CPAN
<http://search.cpan.org/dist/Data-Lock>

COPYRIGHT & LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.