Object-oriented Software in Ada 95

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Contents
4.21 EXERCISES.............................................................................................................................................................59
5 PROCEDURES AND FUNCTIONS ..........................................................................................................60
5.1 INTRODUCTION ...................................................................................................................................................60
5.2 FUNCTIONS...........................................................................................................................................................60
5.2.1 Local variables............................................................................................................................................ 61
5.2.2 Separate compilation of functions............................................................................................................ 61
5.3 PROCEDURES........................................................................................................................................................62
5.3.1 Separate compilation of procedures........................................................................................................ 63
5.4 FORMAL AND ACTUAL PARAMETERS ..........................................................................................................64
5.5 MODES OF A PARAMETER TO A FUNCTION OR PROCEDURE .................................................................64
5.5.1 Example of mode in out ........................................................................................................................ 65
5.5.2 Putting it all together ................................................................................................................................. 65
5.5.3 Summary of access to formal parameters ............................................................................................... 66
5.6 RECURSION...........................................................................................................................................................66
5.6.1 The procedure Write_Natural.......................................................................................................... 67
5.6.2 Putting it all together ................................................................................................................................. 67
5.7 OVERLOADING OF FUNCTIONS.......................................................................................................................67
5.8 DIFFERENT NUMBER OF PARAMETERS........................................................................................................69
5.9 DEFAULT VALUES AND NAMED PARAMETERS..........................................................................................69
5.9.1 Putting it all together ................................................................................................................................. 70
5.10 SELF-ASSESSMENT .............................................................................................................................................71
5.11 EXERCISES.............................................................................................................................................................71
6 PACKAGES AS CLASSES ..........................................................................................................................73
6.1 INTRODUCTION ...................................................................................................................................................73
6.2 OBJECTS, MESSAGES AND METHODS ...........................................................................................................74
6.3 OBJECTS, MESSAGES AND METHODS IN ADA ............................................................................................74
6.3.1 An object for a bank account .................................................................................................................... 75
6.3.2 The procedure Statement..................................................................................................................... 76
6.3.3 Putting it all together ................................................................................................................................. 76
6.3.4 Components of a package.......................................................................................................................... 76
6.3.5 Specification of the package ..................................................................................................................... 76
6.3.6 A class diagram showing a class.............................................................................................................. 78
6.3.7 Representation of the balance of the account........................................................................................ 78
6.3.8 Implementation of the package................................................................................................................. 78
6.3.9 Terminology................................................................................................................................................. 79
6.4 THE PACKAGE AS SEEN BY A USER...............................................................................................................79
6.5 THE PACKAGE AS SEEN BY AN IMPLEMENTOR .........................................................................................79
6.6 THE CLASS............................................................................................................................................................80
6.7 CLAUSES WITH AND USE..................................................................................................................................80
6.7.1 To use or not to use the use clause ........................................................................................................ 81
6.7.2 The package Standard........................................................................................................................... 81
6.7.3 Positioning of with and use in a package declaration .................................................................... 81
6.7.4 Conflict in names in a package ................................................................................................................ 82
6.8 MUTATORS AND INSPECTORS.........................................................................................................................82
6.9 TYPE PRIVATE ......................................................................................................................................................83
6.9.1 Type limited private ...................................................................................................................... 83
6.10 INITIALIZING AN OBJECT AT DECLARATION TIME...................................................................................84
6.10.1 By discriminant ........................................................................................................................................... 84
6.10.2 Restrictions.................................................................................................................................................. 85
6.10.3 By assignment.............................................................................................................................................. 85
6.10.4 Restrictions.................................................................................................................................................. 86
6.11 A PERSONAL ACCOUNT MANAGER ...............................................................................................................86
6.12 CLASS TUI............................................................................................................................................................89
6.13 SELF-ASSESSMENT .............................................................................................................................................91
6.14 EXERCISES.............................................................................................................................................................92
© M A Smith - May not be reproduced without permission