Works::BaseWork

Works::

WorkBehaviors

PCDM::

ObjectBehaviors

Sufia::GenericWork

Sufia::

WorkBehaviors

Works::

HasMetadata

etc...

Sufia::

ModelMethods

etc...

Dissertation

ScannedBook

GISDataset

PCDM::Object

​

Connect the Dots

​

The blue items all exist in their corresponding code bases. Squares represent classes, Plus signs (“+”) represent modules.

​

What are the different ways you can get the desired behaviors to cascade from top to bottom so that they all will be present in the classes at the bottom (ie. Sufia::GenericWork, Dissertation, etc)?

​

See your options in the other slides...

​

​

​

Works::BaseWork

Works::

WorkBehaviors

PCDM::

ObjectBehaviors

Sufia::GenericWork

Sufia::

WorkBehaviors

Works::

HasMetadata

etc...

Sufia::

ModelMethods

etc...

Dissertation

ScannedBook

GISDataset

PCDM::Object

Single-Inheritance

​

This approach uses single inheritance, but the actual behaviors are all in modules that could be mixed together using multiple inheritance.

​

Note: Making Works::BaseWork a subclass of PCDM::Object would prevent the “mixins-only” approach in Slide 3 because we would not be able to make Works::WorkBehaviors include PCDM::ObjectBehaviors

Works::BaseWork

Works::

WorkBehaviors

PCDM::

ObjectBehaviors

Sufia::GenericWork

Sufia::

WorkBehaviors

Works::

HasMetadata

etc...

Sufia::

ModelMethods

etc...

Dissertation

ScannedBook

GISDataset

PCDM::Object

​

Multiple Inheritance

​

(In ruby vernacular, people often talk about this in terms of “mixins” not inheritance)

​

This approach uses only mixins/modules, with no Superclass relationship. Though PCDM:Object, Works:BaseWork and Sufia:GenericWork are available for others to use as superclasses, this implementation doesn’t use them.

​

Note: This would not prevent downstream code from using inheritance (see slide 4).

​

​

Works::BaseWork

Works::

WorkBehaviors

PCDM::

ObjectBehaviors

Sufia::GenericWork

Sufia::

WorkBehaviors

Works::

HasMetadata

etc...

Sufia::

ModelMethods

etc...

PCDM::Object

If Sufia Chooses to use Single Inheritance

​

This shows how something downstream of hydra-pcdm and hydra-works can choose to use single inheritance without this blocking others from using multiple inheritance (mixins).

Dissertation

ScannedBook

GISDataset