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Context-Set-0.02
River stage zero No dependents
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/ Context::Set

NAME

Context::Set - A Contextual preference/configuration holder.

VERSION

Version 0.01

INTRODUCTION

Context is a preference manager that aims at solving the problem of storing configuration properties accross an ever growing collection of contexts that often characterises enterprise systems.

For instance, you might want to have a 'page colour' setting that is global to your system, but allow users to choose their own if they want.

Additionally, you might want to allow your users to specifically define a page color when they view a specific 'list of stuff' in your system. Or allow the system to specify a page color for all lists, or a specific one to certain lists, but still allowing users to override that.

Multiplication of preferences and management of their priorities can cause a lot of confusion and headaches. This module is an attempt to help you to keep those things tidy and in control.

SYNOPSIS

To use Context, the best way is probably to use a Context::Set::Manager that will keep your contexts tidy for you.

  my $cm = Context::Set::Manager->new();
  $cm->universe()->set_property('page.colour' , 'blue');

  my $users = $cm->restrict('users');
  $users->set_property('page.colour', 'green');

  my $user1 = $cm->restrict('users' , 1);
  $user1->set_property('page.colour' , 'red');


  $user1->get_property('page.colour'); # red

  my $user2 = $cm->restrict('users' , 2);
  $user2->get_property('page.colour') ; # green

  my $lists = $cm->restrict('lists');
  my $list1 = $cm->restrict->($lists, 1);

  my $u1l1 = $cm->unite($user1, list1);
  $u1l1->set_property('page.colour', 'purple');

  $u1l1->get_property('page.colour'); # purple

  my $u1l2 = $cm->unite($user1 , $cm->restrict('lists' , 2));
  $u1l2->get_property('page.colour') ; # red

PERSISTENCE

To make context properties persistent accross instances of your application, see Context::Set::Manager

METHODS

fullname

Returns the fully qualified name of this context. The fullname of a context identifies the context in the UNIVERSE in a unique manner.

name

Returns the local name of this context. fullname is more useful.

is_inside

Returns true if this storage is inside a context matching the given name.

Note that this excludes this Context::Set

Usage:

 if( $this->is_inside('users') ){ ... }

has_property

Returns true if there is a property of this name in this context.

Usage:

 if( $this->has_property('pi') ){
    ...
 }

get_property

Gets the property that goes by the given name. Dies if no property with the given name can be found.

my $pi = $this->get_property('pi');

set_property

Sets the given property to the given value. Never dies.

Usage:

  $this->set_property('pi' , 3.14159 );
  $this->set_property('fibo', [ 1, 2, 3, 5, 8, 12, 20 ]);

delete_property

Deletes the given property from this context. Dies if no property with this name exists.

Returns the current value of this property (so you have a chance to look at it a last time before it goes away).

Usage:

  my $deleted_value = $this->delete_property('pi');

lookup

Returns the context holding the given property or undef if none is found.

Usage:

  if( my $holder_context = $context->lookup('pi') ){
     ## $holder_context is the first context holding this property.
  }

unite

Returns the Context::Set::Union of this and the other context.

usage:

  my $u = $this->unite($other_context);

restrict

Produces a new Context::Set::Restriction of this one.

Usage:

  ## Restrict to all users.
  my $context = $this->restrict('users');

  ## Further restriction to user 1
  $context = $context->restrict('1');

AUTHOR

Jerome Eteve, <jerome.eteve at gmail.com>

BUGS

Please report any bugs or feature requests to bug-context at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Context::Set. 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 Context::Set

You can also look for information at:

LICENSE AND COPYRIGHT

Copyright 2012 Jerome Eteve.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.