The CTAT Component hierarchy and SAIs - CMUCTAT/CTAT GitHub Wiki

The JavaScript code for the CTAT components described at HTML Component Overview is maintained in a prototype inheritance hierarchy. In the code in HTML5/src/, the base classes for the individual components are in CTATComponents/ while the superclasses are in CTATComponentHierarchy/. You follow the chain of inheritance through these calls at the bottom of each class's code:

thisClass.prototype = Object.create(parentClass.prototype);

Hence, for CTATTextInput,

• CTATTextInput.prototype = Object.create(CTATTextBasedComponent.prototype); in CTATComponents/CTATTextInput.js
• CTATTextBasedComponent.prototype = Object.create(CTAT.Component.Base.Tutorable.prototype); in CTATComponentHierarchy/CTATTextBasedComponent.js
• CTAT.Component.Base.Tutorable.prototype = Object.create(CTAT.Component.Base.SAIHandler.prototype); in CTATTutorableComponent.js
• CTAT.Component.Base.SAIHandler.prototype = Object.create(CTAT.Component.Base.Graphical.prototype); in CTATComponentHierarchy/CTATSAIHandler.js
• CTAT.Component.Base.Graphical.prototype = Object.create(CTAT.Component.Base.Style.prototype); in CTATComponentHierarchy/Graphical.js
• CTATCompBase.prototype = Object.create(CTATBase.prototype); in CTATComponentHierarchy/CTATCompBase.js

An SAI is, at bottom, a generalized means to describe a user action on a GUI encoded as a 3-element tuple (selection, action, input). Its elements:

• S = selection = a unique identifier for the interactive component, from the id attribute of the HTML element;
• A = action = a verb describing the action taken, often corresponding to a method name on the component instance; e.g. UpdateTextField for a text component;
• I = input = the object of the action; for a text field, what you typed; for a radio button group, the individual button clicked; etc.

Each student action in a tutor is encoded into an SAI by the component and passed to the tracer for grading. An example-tracing tutor's tracer searches the behavior graph for links whose SAIs match the student's SAI, in order to determine whether the student's step is on a path to a solution.