Use design patterns to step up your object-oriented ABAP game, starting with MVC! Want to create objects only when needed? Call objects only when required, minimizing runtime and memory costs? Reduce errors and effort by only coding an object once? Future-proof your code with a flexible design? Design patterns are the answer! With this guide, you'll get practical examples for every design pattern that will have you writing readable, flexible, and reusable code in no time!Highlights include:- MVC (model, view, controller) pattern-Singleton pattern-Factory pattern-Builder pattern-Observer pattern-Visitor pattern-Lazy initialization pattern-Template method-Strategy pattern-Decorator pattern-ABAP-specific examples-Anti-patterns Highlights: MVC (model, view, controller) patternSingleton patternFactory patternBuilder patternObserver patternVisitor patternLazy initialization patternTemplate methodStrategy patternDecorator patternABAP-specific examplesAnti-patterns

Dr. Kerem Koseoglu is a freelance SAP software architect, working professionally since 2000. He specializes in the development of comprehensive applications using design patterns and also conducts technical training related to design patterns. He has participated in global software development projects, taking diverse roles including lead architect, team lead, developer, technical advisor, instructor, and project manager. His former publications include four books and countless articles for technical magazines in Turkey. He has a Ph.D. in organizational behavior.

... Design Pattern Categories ... 19 ... How to Learn ... 20 1.1 ... Case Study: Read, Process, Display, and Post ... 28 1.2 ... Passing Select Options ... 33 1.3 ... Distributing Application Logic ... 34 1.4 ... Related Patterns ... 34 1.5 ... Summary ... 35 2.1 ... Case Study: Log Analysis ... 40 2.2 ... Related Patterns ... 47 2.3 ... Summary ... 47 3.1 ... Case Study: Jobs for Text Files ... 49 3.2 ... When to Use ... 66 3.3 ... Privacy ... 66 3.4 ... Summary ... 67 4.1 ... Case Study: FI Documents for Parties ... 69 4.2 ... Advantages ... 75 4.3 ... Related Patterns ... 75 4.4 ... Summary ... 76 5.1 ... Case Study: Logging Errors ... 77 5.2 ... Advantages ... 81 5.3 ... Related Patterns ... 81 5.4 ... Summary ... 82 6.1 ... Case Study: Vendor Balance ... 84 6.2 ... When to Use ... 88 6.3 ... When to Avoid ... 88 6.4 ... State Modification ... 89 6.5 ... Summary ... 89 7.1 ... Case Study: Item Clone ... 91 7.2 ... Changing Class Properties ... 95 7.3 ... Clone Operations ... 96 7.4 ... Related Patterns ... 96 7.5 ... Summary ... 97 8.1 ... Case Study: Subcomponents ... 99 8.2 ... Advantages and Disadvantages ... 106 8.3 ... Related Patterns ... 106 8.4 ... Summary ... 106 9.1 ... Case Study: Project Management Tools ... 109 9.2 ... Glue Code ... 118 9.3 ... Two-Way Adapters ... 118 9.4 ... Legacy Classes ... 122 9.5 ... Summary ... 122 10.1 ... Case Study: Messaging Framework ... 123 10.2 ... Advantages ... 131 10.3 ... Summary ... 131 11.1 ... Recursive Programming: A Refresher ... 133 11.2 ... Case Study: HR Positions ... 137 11.3 ... Advantages ... 144 11.4 ... Disadvantages ... 144 11.5 ... When to Use ... 145 11.6 ... Related Patterns ... 145 11.7 ... Summary ... 146 12.1 ... Case Study: Potential Customers ... 147 12.2 ... Redundant Code Prevention ... 152 12.3 ... Related Patterns ... 153 12.4 ... Summary ... 153 13.1 ... Case Study: User Exit ... 155 13.2 ... Advantages and Challenges ... 161 13.3 ... Related Patterns ... 162 13.4 ... Summary ... 162 14.1 ... Case Study: Bonus Calculation ... 166 14.2 ... When and Where to Use ... 168 14.3 ... Related Patterns ... 170 14.4 ... Summary ... 170 15.1 ... Case Study: Negative Stock Forecast ... 171 15.2 ... Disadvantages ... 181 15.3 ... When to Use ... 181 15.4 ... Related Patterns ... 182 15.5 ... Summary ... 182 16.1 ... Case Study: Enhancing an SAP Program ... 185 16.2 ... Static vs. Instance Containers ... 194 16.3 ... Sharing Variables ... 195 16.4 ... Variable Uniqueness ... 196 16.5 ... Related Patterns ... 196 16.6 ... Summary ... 198 17.1 ... Case Study: Sensitive Salary Information ... 199 17.2 ... When to Use ... 206 17.3 ... Related Patterns ... 207 17.4 ... Summary ... 207 18.1 ... Case Study: Purchase Order Approver Determination ... 209 18.2 ... Risks ... 217 18.3 ... Related Patterns ... 217 18.4 ... Summary ... 218 19.1 ... Case Study: SD Documents ... 221 19.2 ... When to Use or Avoid ... 229 19.3 ... Related Patterns ... 229 19.4 ... Summary ... 230 20.1 ... Case Study: Stock Movement Simulation ... 232 20.2 ... When to Use ... 241 20.3 ... Disadvantages ... 241 20.4 ... Summary ... 241 21.1 ... Case Study: Budget Planning ... 243 21.2 ... Risks ... 252 21.3 ... Redo ... 253 21.4 ... Summary ... 254 22.1 ... Case Study: Target Sales Values ... 256 22.2 ... Advantages ... 261 22.3 ... Disadvantages ... 261 22.4 ... Multiple Subjects ... 262 22.5 ... Related Patterns ... 263 22.6 ... Summary ... 264 23.1 ... Case Study: Address Builder ... 266 23.2 ... Extensions ... 274 23.3 ... Related Patterns ... 275 23.4 ... Summary ... 275 24.1 ... Case Study: Authorization-Based Class Behavior ... 277 24.2 ... Advantages ... 283 24.3 ... Related Patterns ... 284 24.4 ... Summary ... 284 25.1 ... Case Study: Sending Material Master Data ... 286 25.2 ... Advantages ... 291 25.3 ... Passing Data to the Strategy Object ... 291 25.4 ... Optional Strategies ... 293 25.5 ... Intermediate Abstract Classes ... 297 25.6 ... Related Patterns ... 302 25.7 ... Summary ... 302 26.1 ... Case Study: Average Transaction Volume ... 306 26.2 ... When to Use ... 318 26.3 ... Advantages and Risks ... 319 26.4 ... Degree of Abstraction ... 320 26.5 ... The “Hollywood Principle” ... 320 26.6 ... Summary ... 321 27.1 ... Case Study: Incoming Invoice Processing ... 323 27.2 ... When to Use ... 333 27.3 ... Related Patterns ... 334 27.4 ... Summary ... 335 A ... Object-Oriented Programming ... 339 B ... Subclass Determination ... 361 C ... Principles ... 371 D ... The Author ... 383