Programming in XPCE/Prolog: Section 8.2

## 8.2 Class variable and instance variables

Class-variables may be used as defaults for instance-variables that can be modified through the `Defaults` file. For example, class text defines both the instance- and class-variable font. The class-variable defines the default font, while the font can be modified explicitely at instance-initialisation, or using the `->`font method afterwards.

If a class defines both an instance- and a class-variable with the same name, object-allocation will use the constant @class_default for the initial value of the slot. First access will replace this value using the value from the class-variable.

Instance-variables supercede class-variables for get-behaviour. To access the class-variable explicitly, use the methods from section 8.1.