Wing can watch debug data values using a variety of techniques for tracking the value over time. In most cases, watching a value is initiated by right-clicking a value within a Stack Data view and selecting one of the Watch menu items. The value is then added to the list in the Watch tool and tracked by one of the following methods:

For any of these, if the value cannot be evaluated because it does not exist, the debugger displays <undefined>. This happens when the last object reference to a reference-tracked value is discarded, or if a selected symbolic path is undefined or cannot be evaluated.

The Watch tool will remember watch points across debug sessions, except those that make use of an object reference, which do not survive the debug process.