Back to Basics Designing Classes (part 1 of 2) Klaus Iglberger, CppCon 2021 klaus.iglberger@gmx.de2 Klaus Iglberger C++ Trainer/Consultant Author of the C++ math library (Co-)Organizer Beck, TDD by Example)The Challenge of Class Design 10 Guideline: Design classes for easy change. Guideline: Design classes for easy extensions.Design Guidelines 11 Back to Basics: Class Design (Part ) const; 23 Using inheritance naively to solve our problem easily leads to … … many derived classes; … ridiculous class names; … deep inheritance hierarchies; … duplication between similar implementations

Back to Basics Designing Classes (part 1 of 2) Klaus Iglberger, CppCon 2021 klaus.iglberger@gmx.de2 Klaus Iglberger C++ Trainer/Consultant Author of the C++ math library (Co-)Organizer duplication to enable you to change everything in one place (the DRY principle). Guideline: Design classes for easy change.Data Member Initialization 24 struct Widget { Widget() : Widget(42) // Decisions 63 Guideline: Encapsulate design decisions (i.e. variation points). Guideline: Design classes for easy change.Qualified/Modified Member Data 64 Back to Basics: Class Design (Part 1) The Challenge

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Unit Testing Support Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.4. Support Classes for Integration Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Configuration with Component Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Mixing XML, Groovy Scripts, and Component Classes. . . . . . . . . . . . . . .

Jumps Classes and Objects Classes and Inheritance Properties and Fields Interfaces Visibility Modifiers Extensions Data Classes Sealed Classes Generics Nested and Inner Classes Enum Classes Object Object Expressions and Declarations Inline classes Delegation Delegated Properties Functions and Lambdas Functions 5 5 7 8 9 11 12 14 23 29 33 35 36 36 42 47 62 62 69 71 74 76 databases through their Java drivers. For JPA, the kotlin-jpa compiler plugin adapts Kotlin-compiled classes to the requirements of the framework. Kotlin applications can be deployed into any host that supports

Basics Basic Types Packages Control Flow: if, when, for, while Returns and Jumps Classes and Objects Classes and Inheritance Properties and Fields Interfaces Visibility Modifiers 7 7 9 11 103 111 115 118 2 Extensions Data Classes Sealed Classes Generics Nested and Inner Classes Enum Classes Object Expressions and Declarations Inline classes Delegation Delegated Properties Functions databases through their Java drivers. For JPA, the kotlin-jpa compiler plugin adapts Kotlin- compiled classes to the requirements of the framework. Kotlin applications can be deployed into any host that supports

components @Component and further stereotype annotations Meta-annotations Automatically detecting classes and registering bean definitions Using filters to customize scanning Defining bean metadata within definitions Conditionally include @Configuration classes or @Bean methods Combining Java and XML configuration XML-centric use of @Configuration classes @Configuration class-centric use of XML with @ImportResource Operator Safe Navigation operator Collection Selection Collection Projection Expression templating Classes used in the examples 11. Aspect Oriented Programming with Spring Introduction AOP concepts Spring

. . . . . . . . . . . 85 6 Classes 86 6.1 Class definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 6.2 Abstract and sealed classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 11 Objective-Pascal Classes 159 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 11.10Enumeration in Objective-C classes . . . . . . . . . . . . . . . . . . . . . . . . . . 167 12 Expressions 169 12.1 Expression syntax

components @Component and further stereotype annotations Meta-annotations Automatically detecting classes and registering bean definitions Using filters to customize scanning Defining bean metadata within definitions Conditionally include @Configuration classes or @Bean methods Combining Java and XML configuration XML-centric use of @Configuration classes @Configuration class-centric use of XML with @ImportResource Operator Safe Navigation operator Collection Selection Collection Projection Expression templating Classes used in the examples 11. Aspect Oriented Programming with Spring Introduction AOP concepts Spring

Lambda expressions Lambda expressions practice Next step Classes Properties Create instance Access properties Member functions Data classes Practice Next step Null safety Nullable types Check companions of interfaces Nested declarations in annotation classes Parameterless main Functions with big arity Progressive mode Inline classes Unsigned integers @JvmDefault Standard library Tooling definition and imports Program entry point Print to the standard output Functions Variables Creating classes and instances 308 311 313 313 313 314 314 314 314 315 319 322 322 323 323 324 324

.................................................................. 112 Automatically detecting classes and registering bean definitions ........................ 113 Using filters to customize scanning ...................................................... 134 Conditionally include @Configuration classes or @Bean methods .............. 138 Combining Java and XML configuration ....................... ..................................................................................... 211 10.5. Classes used in the examples ........................................................................ 212