NAME

Class::Prevayler - Prevayler implementation - www.prevayler.org

SYNOPSIS

  use Class::Prevayler;

  my $prevayler = Class::Prevayler->new(
                        system          => new Your::System,
                        directory       => 'prevayler/demo/'
                );

  $prevayler->start();

  my $cmd_obj = Your::Command::Object->new();

  $prevayler->execute( $cmd_obj );

  $prevayler->take_snapshot();

DESCRIPTION

THIS IS BETA-SOFTWARE!!

Class::Prevayler - aka 'Perlvayler' - is a Perl implementation of the prevayler concept.

You can find an introduction to this concept on www.prevayler.org.

This module overloads the 'time', 'localtime' and 'gmtime' functions to make the system deterministic.

USAGE

new

 Usage     : $prevayler->new()
 Purpose   : creates a new object 
 Returns   : the new prevayler-object
 Argument  : you can use key-value pairs to initialize the attributes

start

 Usage     : $prevayler->start()
 Purpose   : recovers the old system state
 Returns   : nothing
 Argument  : none
 Comments  : You have to call it before you can use execute(), even if there is no old serialized state

start

 Usage     : $prevayler->execute()
 Purpose   : execute one command object on the system, and log it
 Returns   : nothing
 Argument  : command object
 Comments  : all command objects must implement a 'execute()' method

take_snapshot

 Usage     : $prevayler->take_snapshot()
 Purpose   : produce a serialized image of the system 
 Returns   : nothing
 Argument  : command object
 Comments  : all command objects must implement a 'execute()' method

system

 Usage     :    $prevayler->system( new My::System )
                my $system = $prevayler->system();
 Purpose   : access to the prevalent system 
 Returns   : returns the actual system if called without argument
 Argument  : new prevalent system

directory

 Usage     :    $prevayler->directory( './prevayler/' )
                my $directory = $prevayler->directory();
 Purpose   : sets the directory where all serialized objects are stored 
 Returns   : returns the actual directory if called without argument
 Argument  : new directory

serializer

 Usage     :    $prevayler->serializer( \&mySerializer )
                my $serializer = $prevayler->serializer();
 Purpose   : define the serializer. 
                The serializer is called with a structure (an object)
                and returns a string representation of this structure.
                The default serializer is implemented with Data::Dumper.
 Returns   : returns the actual serializer if called without argument
 Argument  : reference to a subroutine

deserializer

 Usage     :    $prevayler->deserializer( \&myDeSerializer )
                my $deserializer = $prevayler->deserializer();
 Purpose   : define the deserializer. 
                The deserializer is called with a serialized structure
                and returns this structure.
                The default deserializer is implemented with eval.
 Returns   : returns the actual deserializer if called without argument
 Argument  : reference to a subroutine

BUGS

- none known, but: this is beta-software, there will be API and fileformat changes.

AUTHOR

        Nathanael Obermayer
        CPAN ID: nathanael
        natom-pause@smi2le.net

COPYRIGHT

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

The full text of the license can be found in the LICENSE file included with this module.

SEE ALSO

perl(1).

http://www.prevayler.org

cpanm Class::Prevayler

perl -MCPAN -e shell
install Class::Prevayler