Documentation/Labs/ModulesAndEvents

This page keeps track of Greg's notes on how to hook up module events

Motivation

• Getting things working in Slicer can be hairy
• There is not always the right kind of documentation for what you want to do.
• The goal of this page is to take some notes on this process for eventual inclusion in the developer documentation.
• Scope is limited to C++ development

MRML nodes

• MRML nodes are used to store persistent state. You need to use MRML nodes if you want to save and restore slicer scenes.
• MRML nodes can emit events. To emit an event, do ??
• MRML nodes can receive events. To receive an event, define a function called ProcessMRMLEvents(). This function receives all requested events as an (object, event id) pair. The event id might or might not be unique.

Logic classes

• Logic classes implement processes. They serve purposes such as:
  • Implement helper logic for widget classes, so that all business logic can be performed without the need of a GUI
  • Implement filter-type logic, which manipulates MRML nodes without need for persistent state
• There may be multiple logic classes associated with a single MRML node

MRML nodes and multithreading

• Slicer is implemented as a single threaded process
• Therefore, there is no need to implement transaction logic to ensure atomicity when modifying multiple MRML nodes