Jot]rnal 23 ,rrhp-rt Beal-iime Operating System, by Kevin D. Morgan 27 Oroverview Ol Threads 3 1 Managing Pa-risc Machines for Real-time Systems

Data Types.Abstract data types represent the inter-face to more than one implementation of a common' usuallycomplicated concept. Because an abstract data$pe is abaseclass to more than one derived class, it must contain at leastone pure virtual function. Objects of this type can only becreated through derivation in which the pure virtual functionimplementation is filled in by the derived classes' The following is an example of an abstract base class: classpolygon{oub l i c : / / constructor,destructorandothermemberfunctions / / cou ldgohere . . .virtualvoidrotate{ inti l=0; l lapurevirtualfunction/ / o ther func t ionsgohere . . . \;Realizing Productivity Gains with C++ Althoughc++containsmanyfeaturesforsupportinghi hlyproductive softwaredevelopment,s0mecharacteristicsof thisobject-orientedprogramminglanguagetendto s lowthereal izat ion0f theseproductivitygains. by fimothy C. O'Konski August1993Hewlett-PackarclJoumal 85