CPSC 320: Week 16

• Stepwise Refinement


• Abstract Data Objects: When using a package to define an Abstract Data Object the package implementation contains declarations of variables that the client accesses and manipulates using the operations in the specification. The client accesses the object by instantiating and useing the package. Thus the client can only access more than one such object (eg more than one stack) by instantiating the package several times.
• Stack Abstract Object specification
• Stack Abstract Object implementation
• Stack Abstract Object usage


• Exam Topics


• In case you're curious: more OO in Ada
• A sample project
• Inputs a list of employees that are salaried or wage and calculates their pay and prints two lists: employees sorted by id, and ascending salaries only
• p3.adb contains the main program
• all_emp.ads/b contains the employee package
• a generic list package is also included
• Tagged record types can be extended with new fields
• Parameters of type Type'Class allows parameters of subclass type
• Polymorphism is only possible when using pointers