&2%2/ Issue 2b, March 2004 REMHFWRULHQWHG SURJUDPPLQJZLWKFRERO 2EMHFWRULHQ WHG oppubb.book Page 1 Tuesday, March 16, 2004 12:23 PM Copyright © 2004 Micro Focus International Limited. All rights reserved. Micro Focus International Limited has made every effort to ensure that this book is correct and accurate, but reserves the right to make changes without notice at its sole discretion at any time. The software described in this document is supplied under a license and may be used or copied only in accordance with the terms of such license, and in particular any warranty of fitness of Micro Focus software products for any particular purpose is expressly excluded and in no event will Micro Focus be liable for any consequential loss. Animator®, COBOL Workbench®, EnterpriseLink®, Mainframe Express®, Micro Focus®, Net Express®, REQL® and Revolve® are registered trademarks, and AAI™, Analyzer™, Application to Application Interface™, AddPack™, AppTrack™, AssetMiner™, CCI™, DataConnect™, Dialog System™, EuroSmart™, FixPack™, LEVEL II COBOL™, License Management Facility™, License Server™, Mainframe Access™, Mainframe Manager™, Micro Focus COBOL™, Object COBOL™, OpenESQL™, Personal COBOL™, Professional COBOL™, Server Express™, SmartFind™, SmartFind Plus™, SmartFix™, SourceConnect™, Toolbox™, WebSync™, and Xilerator™ are trademarks of Micro Focus International Limited. All other trademarks are the property of their respective owners. No part of this publication, with the exception of the software product user documentation contained on a CD-ROM, may be copied, photocopied, reproduced, transmitted, transcribed, or reduced to any electronic medium or machine-readable form without prior written consent of Micro Focus International Limited. Licensees may duplicate the software product user documentation contained on a CD- ROM, but only to the extent necessary to support the users authorized access to the software under the license agreement. Any reproduction of the documentation, regardless of whether the documentation is reproduced in whole or in part, must be accompanied by this copyright statement in its entirety, without modification. U.S. GOVERNMENT RESTRICTED RIGHTS. It is acknowledged that the Software and the Documentation were developed at private expense, that no part is in the public domain, and that the Software and Documentation are Commercial Computer Software provided with RESTRICTED RIGHTS under Federal Acquisition Regulations and agency supplements to them. Use, duplication or disclosure by the U.S. Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of The Rights in Technical Data and Computer Software clause at DFAR 252.227-7013 et. seq. or subparagraphs (c)(1) and (2) of the Commercial Computer Software Restricted Rights at FAR 52.227-19, as applicable. Contractor is Micro Focus, 9420 Key West Avenue, Rockville, Maryland 20850. Rights are reserved under copyright laws of the United States with respect to unpublished portions of the Software. 20040316122346 oppubb.book Page 2 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 3 Table of Contents About this Book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Command Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Side Headings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Part 1: Overview 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Object-oriented COBOL syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Developing OO Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 What to Read Next. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Object-oriented Analysis and Design . . . . . . . . . . . . . . . . . . . . . . . . 19 2 OO Programming Concepts . . . . . . . . . . . . . . . . . . . 21 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Polymorphism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 oppubb.book Page 3 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 4 Part 2: Object-oriented COBOL Programming 3 Using Objects in Programs . . . . . . . . . . . . . . . . . . . . 33 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Declaring Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Using Object References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Declaring Object References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Manipulating Object References . . . . . . . . . . . . . . . . . . . . . . . . . 36 Object Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Sending Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Using the INVOKE Statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Inline Method Invocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Invocation Using Object Properties . . . . . . . . . . . . . . . . . . . . . . . 40 Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Creating a New Instance Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Destroying Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Object Destruction Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Finalized Object References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4 Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Class Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Inheritance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Method Inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Data Inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Files in OO Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Programming Factory Object Behavior . . . . . . . . . . . . . . . . . . . . . . . 56 Factory Object Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Class Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Factory Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Programming Instance Object Behavior . . . . . . . . . . . . . . . . . . . . . . 58 Instance Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Instance Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Instance Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 oppubb.book Page 4 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 5 Parameterized Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 5 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Method Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Predefined Object Reference Names . . . . . . . . . . . . . . . . . . . . . . . . 67 Instance Creation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Get and Set Property Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 PROPERTY Clause in a Data Item Definition . . . . . . . . . . . . . . . 72 PROPERTY Clause in a Method Definition . . . . . . . . . . . . . . . . . 72 Coding the Object Property Syntax . . . . . . . . . . . . . . . . . . . . . . 73 6 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Interface Source Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Interface Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Parameterized Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 7 Compiling and Debugging OO COBOL Applications 81 Compiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Compiler Directives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Directly Inherited Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Preventing Reallocation of Object Handles . . . . . . . . . . . . . . . . 84 Finding Memory Leaks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Object Data Guard Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Message Tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Troubleshooting Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Memory Exceptions and Protection Violations on Method Invocations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Symbol Redefined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Program Not Found . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 oppubb.book Page 5 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 6 Part 3: Tutorials 8 Objects and Messages Tutorial. . . . . . . . . . . . . . . . . 95 The Stopwatch Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Sending Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 9 Simple Class Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . 101 Structure of a Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Identifying a Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Identifying Classes Used by a Program . . . . . . . . . . . . . . . . . . . . 102 The Factory Object Source Element . . . . . . . . . . . . . . . . . . . . . . . 103 Factory Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 The Instance Object Source Element . . . . . . . . . . . . . . . . . . . . . . 104 Instance Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Animating the Stopwatch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10 More Complex Class Tutorial . . . . . . . . . . . . . . . . . . 111 The Personnel Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Exploring the Personnel Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Animating the Personnel Application . . . . . . . . . . . . . . . . . . . . . . . . 114 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 11 Interfaces and Parameterized Class Tutorial . . . . . . 119 The PClass Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Exploring the Pclass Classes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Animating the Pclass Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 oppubb.book Page 6 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 7 Part 4: Micro Focus OO COBOL Alternatives and Extensions 12 Micro Focus OO COBOL Alternative Syntax . . . . . . 127 Summary of Syntax Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Shared Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Working-Storage Section in a Method . . . . . . . . . . . . . . . . . . . . . . . 129 Working Storage and Object Storage. . . . . . . . . . . . . . . . . . . . . . . . 129 Data Inheritance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Direct Data Inheritance in Source Code . . . . . . . . . . . . . . . . . . . 130 Direct Data Inheritance at Run Time . . . . . . . . . . . . . . . . . . . . . 132 Extending a Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 13 Requirements-based Vocabulary . . . . . . . . . . . . . . . 137 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Defining a Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 External Class Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 Method Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 User-defined Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Using Vocabulary-defined Verbs and Functions. . . . . . . . . . . . . . . . 141 Part 5: Micro Focus Class Libraries 14 Introduction to the Class Libraries . . . . . . . . . . . . . . 145 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Public and Private Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Class Library Method Parameter Types . . . . . . . . . . . . . . . . . . . . . . . 147 Class Library Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Frameworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Animating the Class Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 oppubb.book Page 7 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 8 15 Collection Frameworks . . . . . . . . . . . . . . . . . . . . . . . 151 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Different Categories of Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Creating Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Creating Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Working with CharacterArray Objects. . . . . . . . . . . . . . . . . . . . . 156 Creating a CharacterArray Object . . . . . . . . . . . . . . . . . . . . . . . . 156 Querying a CharacterArray Object. . . . . . . . . . . . . . . . . . . . . . . . 157 Comparison Between Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Equality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Relative Value of Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Hashing Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Display Mechanisms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Using the display Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Display on a Listbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Collection Sort Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Iterator Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 16 Intrinsic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Using Intrinsic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Cloning an Intrinsic Data Class . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Sending a Message to an Intrinsic Data Type . . . . . . . . . . . . . . . 167 Writing New Intrinsic Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Code for an Intrinsic Class Object. . . . . . . . . . . . . . . . . . . . . . . . . 168 Code for an Intrinsic Instance Object. . . . . . . . . . . . . . . . . . . . . . 169 17 Callback Frameworks . . . . . . . . . . . . . . . . . . . . . . . . 173 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Using Callbacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Creating a Callback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Invoking a Callback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 oppubb.book Page 8 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 9 18 Exception Handling Frameworks . . . . . . . . . . . . . . . 177 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 Creating an Error Message File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 Registering an Exception Message File. . . . . . . . . . . . . . . . . . . . . . . 179 Raising an Exception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Providing Your Own Exception Handlers . . . . . . . . . . . . . . . . . . . . . 182 Writing Exception Handler Methods . . . . . . . . . . . . . . . . . . . . . 183 Registering an Object with the Exception Handler . . . . . . . . . . 185 Canceling an Exception Registration . . . . . . . . . . . . . . . . . . . . . 185 Replacing the System Exception Method . . . . . . . . . . . . . . . . . . . . . 185 19 Component Frameworks. . . . . . . . . . . . . . . . . . . . . . 187 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Defining Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Defining Input Sockets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Connecting Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Sending Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 Part 6: Micro Focus OO COBOL Tutorials 20 Inheritance Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . 197 The Account Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 Simple Account Transactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 21 Collections, Intrinsics and Dictionaries Tutorial. . . . 203 Collections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Using Intrinsics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208 Dictionaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Iterator Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 oppubb.book Page 9 Tuesday, March 16, 2004 12:23 PM Object-oriented Programming with COBOL 10 22 Exception Handling Tutorial . . . . . . . . . . . . . . . . . . . 215 Raising an Exception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Registering an Exception Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 Writing an Exception Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 23 Requirements-based Vocabulary Tutorial . . . . . . . . 223 Introducing the Vocabulary Example . . . . . . . . . . . . . . . . . . . . . . . . . 223 Using Requirements-based Vocabulary . . . . . . . . . . . . . . . . . . . . . . . 225 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Part 7: Appendices A Descriptions of OO Run-time Switches . . . . . . . . . . 229 List of Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 oppubb.book Page 10 Tuesday, March 16, 2004 12:23 PM [...]... Overview Object- oriented Programming with COBOL oppubb.book Page 17 Tuesday, March 16, 2004 12:23 PM 17 1 Introduction This chapter introduces the facilities for object- oriented programming provided in your COBOL system, and explains how to use this book to begin OO programming with COBOL Object- oriented COBOL syntax Your COBOL system enables you to do object- oriented (OO) programming in COBOL, while... 2: Object- oriented COBOL Programming This part contains the following chapters: • Chapter 3, “Using Objects in Programs” • Chapter 4, “Classes” • Chapter 5, “Methods” • Chapter 6, “Interfaces” • Chapter 7, “Compiling and Debugging OO COBOL Applications” Object- oriented Programming with COBOL oppubb.book Page 32 Tuesday, March 16, 2004 12:23 PM 32 Part 2: Object- oriented COBOL Programming Object- oriented. .. Express on Windows Object- oriented Programming with COBOL 13 oppubb.book Page 14 Tuesday, March 16, 2004 12:23 PM 14 About this Book Object- oriented Programming with COBOL oppubb.book Page 15 Tuesday, March 16, 2004 12:23 PM 15 Part 1: Overview This part contains the following chapters: • Chapter 1, “Introduction” • Chapter 2, “OO Programming Concepts” Object- oriented Programming with COBOL oppubb.book... languageindependent courses on OOD and OOA Object- oriented Programming with COBOL oppubb.book Page 21 Tuesday, March 16, 2004 12:23 PM 21 2 OO Programming Concepts This chapter describes the key concepts supported by an objectoriented programming language, and how they are implemented by Micro Focus COBOL Micro Focus COBOL supports the ISO 2002 standard for Object- Oriented COBOL (OO COBOL) and supplies some additional... anObject "message" • Copy an object reference to another For example: set anObject1 to anObject2 • Test whether two object references refer to the same object For example: if anObject1 = anObject2 Micro Focus Extension • Test whether an object reference refers to an object of a particular class For example: if anObject1 instance of ClassA Object- oriented Programming with COBOL ... some books dealing with objectoriented methodologies and technologies Booch, Grady Object- Oriented Design Benjamin/Cummings, 1994 ISBN: 0-8053-0091-0 Jacobson , Ivor Object- Oriented Software Engineering Addison-Wesley, 1992 ISBN: 0-201-54435-0 Object- oriented Programming with COBOL 19 oppubb.book Page 20 Tuesday, March 16, 2004 12:23 PM 20 Chapter 1 Introduction Rumbaugh James Object- Oriented Modeling... Declaring Object References You need to declare data items of type OBJECT REFERENCE to hold handles to any objects you will be using For example: 01 01 01 01 anObject usage object reference secdObject usage object reference factory of BankAccount thirdObject usage object reference active-class fourthObject usage object reference Rentable The first line defines an untyped or universal object reference Object- oriented. .. the message draw to any graphical object, without caring what type it is The receiver of the message will execute its own draw method, producing the correct result (see Figure 2-6) Object- oriented Programming with COBOL 29 oppubb.book Page 30 Tuesday, March 16, 2004 12:23 PM 30 Chapter 2 OO Programming Concepts Figure 2-6 Polymorphism Object- oriented Programming with COBOL oppubb.book Page 31 Tuesday,... COBOL Alternative Syntax, in Part 4 Object- oriented Programming with COBOL oppubb.book Page 18 Tuesday, March 16, 2004 12:23 PM 18 Chapter 1 Introduction Developing OO Programs Development starts with the analysis of the problem and the design of a program or programs that solve the problem Object- oriented design involves identifying the objects that you want to work with and what they need to do Object- oriented. .. the instance objects it requires For each instance object created, you must declare an object reference to hold the object handle, although you may overwrite the object handle in an object reference with a new one if you have finished with it When a program has finished with an object, it should destroy it Declaring Classes If you want to use an object in a program, you must declare the object s class . to begin OO programming with COBOL. Object- oriented COBOL syntax Your COBOL system enables you to do object- oriented (OO) programming in COBOL, while. 12:23 PM Object- oriented Programming with COBOL 11 About this Book This book explains how to do object- oriented programming in COBOL, using ISO 2002 COBOL,