typedef struct { int kind; } * object;
The library provides a set of graphics routines which work on many different platforms. For this reason the data types defined by the library are neutral to all platforms. Most of the graphical objects defined by this library are simply pointers to a structure containing an integer. This integer is used internally by the library to determine each object's type at run-time, if necessary, facilitating polymorphic functions.
The graphapp.h header file is designed to be platform-neutral as well. It contains no conditional statements asking which platform it is being compiled under. Code which relies only on this header file and library for graphics function definitions is hence guaranteed to be portable with few or no changes.