VOOPS maps classes and member definitions onto C types, structures and unions. A class is translated into a structure definition, with the class members being structure members. Accessor macros are defined for each class member which allow access to class members through verbose names instead of complicated and not obviously comprehensible C structure member access and pointer dereference operators. All classes have a default object identifier member which is used to store a unique ID of the object, when it is newly created with the default New method.
Inheritance is effected through defining the members of the specified
parent class in the currently defined class too. Since all these parent class
members are also included as C structure members, one limitation becomes
obvious: No two members can have the same name, if they appear in the same
inheritance branch of the class tree, since this would produce a name conflict
in the resulting C code. Fig. 5.2 shows how members and methods are
inherited for the example on page 
.
On definition, a unique class name (a LISP symbol) has to be given to a class, which is used as an identifier on subsequent accesses to the class. An optional documentation string given in the class definition is translated into a documentation comment conforming to the VISTA documentation guidelines (see [IuE94]). Besides the documentation string, members can also have alias names which are aliased via a C macro to the original member accessor macro.
A detailed description of the VOOPS implementation, its syntax and a simple example demonstrating some of VOOPS' object-oriented features may be found in Appendix C.