1   Stack Definition Introduction

A stack definition is an object stored within a state definition object implementing an abstraction layer on a stack object instance.

A stack definition:

• defines high level accessors and mutators on the stack object.
• defines the policy of roles distributions for the stack elements stored within the stack using managed roles expressions. It includes as well a specific guard while the stack object doesn't contain elements yet.
• defines the default policy for editing and viewing stack elements using guards. (Note that a stack element has its own guard that may override the default behavior from the stack definition).

It may be used as well without any roles policy if the purpose of the stack is not to distribute local roles. (for instance: adding a stack of tasks hooked on a given state)

2   Stack Definition Registry

If you need to implement a specific behavior, you may register your own stack definition.

You must implement the IWorkflowStackDefinition interface and usually you will inherit from the base StackDefinition class in your child class which is already implementing this interface.

You may use it like this:

>>> from Products.CPSWorkflow.stackregistries import WorkflowStackDefRegistry
>>> from Products.CPSWorkflow.stackdefinition import StackDefinition
>>>
>>> class MyStackDefinition(StackDefinition):
...     # Here implementation
...     pass
>>>
>>> WorkflowStackDefRegistry.register(MyStackDefinition)
1

Check the API in the doc/api/ sub-folder.