A Field determines how data is displayed and stored.
A Field is a component of a data structure. Every Field has a type.
For example, an IntegerField stores a signed integer while a
TextField stores a string.
The value of a Field can be represented as HTML (for display in the
GUI), or as XML (when written to persistent storage). Every Field can
create an HTML form that can be used by the user to update the value of
the Field .
Every Extension class has a set of arguments composed of Field . An
instance of that Extension class can be constructed by providing a
value for each Field object. The GUI can display the Extension
object by rendering each of the Field values as HTML. The user can
change the value of a Field in the GUI, and then write the Extension
object to persistent storage.
Additional derived classes of Field can be created for use in
domain-specific situations. For example, the QMTest Test class
defines a derived class which allows the user to select from among a set
of test names.
|