SPOPSx::Ginsu 0.58

SPOPSx::Ginsu is a SPOPS extension for Generalized INheritance SUpport.

SYNOPSIS

1. Create a datasource class, for example MyDBI, which inherits from SPOPSx::Ginsu::DBI holds the package variables for the database connection (e.g. see t/MyDBI.pm).
2. Create a root base class, for example MyBaseObject, which inherits from the datasource class and SPOPSx::Ginsu and defines the base table (e.g. see t/MyBaseObject.pm).
3. Create your own sub-class of MyBaseObject which defines it's own fields (e.g. see t/Person.pm).
4. Create a configuration file which defines the package variables used by the datasource class to make the database connection (e.g. see t/my_dbi_conf.pm).
Assuming the files from steps 1-4 are MyDBI.pm, MyBaseObject.pm, MyObject.pm and my_dbi_conf.pm ...

use my_dbi_conf;
use MyObject;

$obj = MyObject->new({field1 => 'value1', ... });
$obj = $obj->save;
$obj = MyObject->fetch($id);
$obj = MyBaseObject->pm_fetch($id);

$obj->remove;

This is the base class for all Ginsu objects. SPOPS::DBI implements an inherited persistence mechanism for classes whose objects are each stored as a row in a single database table. Each class has its own table and all of the persistent fields are stored in that table. Ginsu extends this implementation to handle subclassing of such objects, including polymorphic retrieval. The fields of a given object are stored across several database tables, one for each parent class with persistent fields. A Ginsu object is simply an SPOPS::DBI object stored across multiple database tables.

All objects for which you want polymorphic access must share a base class whose table has a unique 'id' field and a 'class' field. In the example classes used for the tests (see the diagram in docs/Example.pdf), this class is called MyBaseObject. Suppose we have a VehicleImplementation class inheriting from MyBaseObject, which has the fields 'name' and 'owner'. And suppose VehicleImplementation has a subclass Aircraft which adds the field 'ceiling'. In this example, an Aircraft object will be stored into 3 tables, 'id' and 'class' in the base_table for MyBaseObject, 'name' and 'owner' in the base_table for VehicleImplementation and 'ceiling' in the base_table for Aircraft. Each table also has an id_field which is used to join the pieces of the object together from the 3 tables.

Also, unlike the typical usage of SPOPS objects, where the classes are created by SPOPS and have no corresponding .pm file, Ginsu objects are defined in a .pm file just like a standard Perl object, with a few additions. Each class must define the variables @ISA, $CONF, and $TABLE_DEF in the BEGIN block. The @ISA variable is standard Perl and $TABLE_DEF contains an SQL statement which creates the table for the corresponding class. The $CONF variable contains an SPOPS configuration hash with the configuration for this class only. The BEGIN block is followed by 'use' statements for the classes which are referenced in @ISA and the 'has_a' and 'links_to' parts of $CONF. Finally, after all of the use statements, it should have the line:

__PACKAGE__->config_and_init;

By convention we put it as the last line of code in the file.

These conventions allow us to say ...

use MyObject;
... just like we would 'use' any other Perl object.

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Requirements:

· Perl