Class fields are fields shared by all the instances of a given interface.
Each Gdome2 object has one instance field which is a pointer to a statically allocated structure containing its class fields. A typical example of a class field which is present in all Gdome2 objects is the virtual table , containing pointers to the methods implemented by the class of the object itself. The use of virtual tables enables us to have a mechanism equivalent to inheritance of methods, thus favoring the reuse of code and making easier the maintenance of the source code.