Subtyping Pattern!¶

Note

In a recent design discussion with Nate Aune he said he thinks some of my common design patterns are really similiar to this approach. After striping away the Plone-isms, I have to say there is merit to what Nate thinks. (Danny 07/05/2011)

by Rocky Burt

What is subtyping?¶

-Allowing for the subtyping of an existing content type

Why subtyping?¶

-Many possible faces for existing content type -simple conversion -delayed specification -not exclusive to p4a.subtyper, just built off of it

use cases ===============-

-Need diferent content identify depending on situation -ogg file is video or audio -transforming of identity based on event reaction -How do you handle when a file type is uploaded?

p4a.subtyper¶

-minimal framework -Hooks up subtypes into content menu -$easy_install p4a.subtyper -use workingenv or virtualenv or buildit as preferred -special subtype events

add ISubtypAdded

addISubtypeRemoved

-extension by adapters and schema’s

demo¶

-new modules interfaces and IUlradoc

IUltadoc os marker interface

interface.alsoProvides(needs marker interface, IContentType)

create descripters module

new descripter class called UltraDocDescriptor

for_portal_type = when this content type is displayed, this descriptor will be provided

create ultraddoc.pt

register descriptor as utility

hook up new view applying to utility

lets you have different views all with files named differently

cases in Plone4Artists¶

-Look at Audio, Video, Calendar

no mention of p4a.subtyper

But uses these techniques