mixin::extrafields::driver::hashguts(3pm) [debian man page]

Mixin::ExtraFields::Driver::HashGuts(3pm)		User Contributed Perl Documentation		 Mixin::ExtraFields::Driver::HashGuts(3pm)

NAME

       Mixin::ExtraFields::Driver::HashGuts - store extras in a hashy object's guts

VERSION

       version 0.008

SYNOPSIS

	 package Your::HashBased::Class;

	 use Mixin::ExtraFields -fields => { driver => 'HashGuts' };

DESCRIPTION

       This driver class implements an extremely simple storage mechanism: extras are stored on the object on which the mixed-in methods are
       called.	By default, they are stored under the key returned by the "default_has_key" method, but this can be changed by providing a
       "hash_key" argument to the driver configuration, like so:

	 use Mixin::ExtraFields -fields => {
	   driver => { class => 'HashGuts', hash_key => "SomethingWicked" }
	 };

METHODS

       In addition to the methods required by Mixin::ExtraFields::Driver, the following methods are provided:

   hash_key
	 my $key = $driver->hash_key;

       This method returns the key where the driver will store its extras.

   default_hash_key
       If no "hash_key" argument is given for the driver, this method is called during driver initialization.  It will return a unique string to
       be used as the hash key.

   storage
       This method returns the hashref of storage used for extras.  Individual objects get weak references to their id within this hashref.

   storage_for
	 my $stash = $driver->storage_for($object, $id);

       This method returns the hashref to use to store extras for the given object and id.  This hashref is stored on both the hash-based object
       (in its "hash_key" entry) and on the driver (in the entry for $id in its "storage" hash).

       All objects with the same id should end up with the same hash in their "hash_key" field.  None of these references are weakened, which
       means two things:  first, even if all objects with a given id go out of scope, future objects with that id will retain the original extras;
       secondly, memory used to store extras is never reclaimed.  If this is a problem, use a more sophisticated driver.

AUTHOR

       This code was written by Ricardo SIGNES.  His code in 2006 was sponsored by Listbox.

COPYRIGHT AND LICENSE

       Copyright (C) 2006, Ricardo SIGNES.  This code is free software, and is available under the same terms as perl itself.

perl v5.10.1							    2010-01-19				 Mixin::ExtraFields::Driver::HashGuts(3pm)

Mixin::ExtraFields::Driver(3pm) 			User Contributed Perl Documentation			   Mixin::ExtraFields::Driver(3pm)

NAME

       Mixin::ExtraFields::Driver - a backend for extra field storage

VERSION

       version 0.008

SYNOPSIS

       This is really not something you'd use on your own, it's just used by Mixin::ExtraFields, but if you insist...

	 my $driver = Mixin::ExtraFields::Driver::Phlogiston->from_args(\%arg);

	 $driver->set($obj, $obj_id, flammable => "very!");

DESCRIPTION

       Mixin::ExtraFields::Driver is a base class for drivers used by Mixin::ExtraFields -- hence the name.  A driver is expected to store and
       retrieve data keyed to an object and a name or key.  It can store this in any way it likes, and does not need to guarantee persistence
       across processes.

SUBCLASSING

       All drivers must implement the four methods listed below.  The base class has implementations of these methods which will die noisily
       ("confess"-ing) when called.

       Almost all methods are passed the same data as their first two arguments: $object, the object for which the driver is to find or alter
       data, and $id, that object's unique id.	While this may be slighly redundant, it keeps the id-finding call in one place.

   from_args
	 my $driver = Mixin::ExtraFields::Driver::Subclass->from_args(\%arg);

       This method must return a driver object appropriate to the given args.  It is not called "new" because it need not return a new object for
       each call to it.  Returning identical objects for identical configurations may be safe for some driver implementations, and it is expressly
       allowed.

       The arguments passed to this method are those given as the "driver" option to the "fields" import group in Mixin::ExtraFields, less the
       "class" option.

   get_all_detailed_extra
	 my %extra = $driver->get_all_detailed_extra($object, $id);

       This method must return all available information about all existing extra fields for the given object.	It must be returned as a list of
       name/value pairs.  The values must be references to hashes.  Each hash must have an entry for the key "value" giving the value for that
       name.

   set_extra
	 $driver->set_extra($object, $id, $name, $value);

       This method must set the named extra to the given value.

   delete_extra
	 $driver->delete_extra($object, $id, $name);

       This method must delete the named extra, causing it to cease to exist.

OPTIMIZING

       The methods below can all be implemented in terms of those above.  If they are not provided by the subclass, basic implementations exist.
       These implementations may be less efficient than implementations crafted for the specifics of the storage engine behind the driver, so
       authors of driver subclasses should consider implementing these methods.

   get_all_extra
	 my %extra = $driver->get_all_extra($object, $id);

       This method behaves like "get_all_detailed_extra", above, but provides the entry's value, not a detailed hashref, as the value for each
       entry.

   get_extra
   get_detailed_extra
	 my $value = $driver->get_extra($object, $id, $name);

	 my $hash = $driver->get_detailed_extra($object, $id, $name);

       These methods return a single value requested by name, either as the value itself or a detailed hashref describing it.

   get_all_extra_names
	 my @names = $driver->get_all_extra_names($object, $id);

       This method returns the names of all existing extras for the given object.

   exists_extra
	 if ($driver->exists_extra($object, $id, $name)) { ... }

       This method returns true if an entry exists for the given name and false otherwise.

   delete_all_extra
	 $driver->delete_all_extra($object, $id);

       This method deletes all extras for the object, as per the "delete_extra" method.

AUTHOR

       This code was written by Ricardo SIGNES.  His code in 2006 was sponsored by Listbox.

COPYRIGHT AND LICENSE

       Copyright (C) 2006, Ricardo SIGNES.  This code is free software, and is available under the same terms as perl itself.

perl v5.10.1							    2010-01-19					   Mixin::ExtraFields::Driver(3pm)