## 20 23 October 01 - 06 ## +23 ## A Journey Into Non-Virtual Polymorphism ## RUDYARD MERRIAM ## Who Doesn't Recognize This??  Cppcon 2023 | Rud Merriam | A Journey into Non-Virtual Polymorphism ## Background ## • Experience with many languages – FORTRAN IV (1968!), PL/M, assembly, C, Turbo Pascal, Forth • Taught for embedded systems (Arduino, Raspberry Pi) - Medium.com (https://medium.com/@rudmerriam) ## Polymorphism • Greek: “many forms” (Obligatory statement) - The use of a single symbol to represent multiple

Programming Key Ideas Early and Late Binding Class Traps Virtuality Inheritance override final Polymorphism Template method Interfaces Destructor Liskov substitution principle Inheritance (interface Programming Key Ideas Early and Late Binding Class Traps Virtuality Inheritance override final Polymorphism Template method Interfaces Destructor Liskov substitution principle Inheritance (interface Programming Key Ideas Early and Late Binding Class Traps Virtuality Inheritance override final Polymorphism Template method Interfaces Destructor Liskov substitution principle Inheritance (interface

1567a25e4/p9_2.jpg) # Six ways for Implementing Math Expressions Calculator A walk through polymorphism, smart pointers, templates, concepts and more Amir Kirsh  << endl; delete e; // to print something like: // ((3 ^ 2) + (-1)) = 8 ## A quick polymorphism exercise Let's start here: http://coliru.stacked-crooked.com/a/192d90699cd08eb5 (Or just /p38_2.jpg) Design Pros: Simple usage, short and concise, hiding implementation details, polymorphism with value semantics Do we need derived classes for Sum and Exp? ## What do you say about something

Static polymorphism ## Generic Programming Same code works on different, unrelated types Static polymorphism ## C++ Templates Same code works on different, unrelated types Static polymorphism ![Ima

CODE AND DATA: GENERIC CLASSES • Curiously Recurring Template Pattern (CRTP) • Compile-time polymorphism - Generic interface, algorithms, data in templated base class • Customization points in derived decision ## RUNTIME ## POLYMORPHISM ## RUNTIME POLYMORPHISM • Design decision! • Strong coupling between types • Share base classes and common interface ## RUNTIME POLYMORPHISM • Design decision! • base classes and common interface • Interface must have same meaning for all types ## RUNTIME POLYMORPHISM • Design decision! • Strong coupling between types • Share base classes and common interface

8a7cbf36a14fa6f12c31d143785f9bc9/p3_2.jpg) function overloading exception handling RAII polymorphism namespace inheritance ## overhead lambda ## Overview  ## Hardware Abstraction Layer • Encapsulation • Inheritance • Polymorphism • Template Metaprogramming  Compiles to the same binary. ## Polymorphism ## Moving Higher Microcontroller ![Image](/uploads/documents/8/a/7/c/8a7cbf36a14fa6f12c31d143785f9bc9/p35_1

factory method pattern design pattern.Use \[edit]OOP provides polymorphism on object use by method dispatch, formally subtype polymorphism via single dispatch determined by the type of the object on which which to dispatch.\[b]Using factories instead of constructors or prototypes allows one to use polymorphism for object creation, not only object use. Specifically, using factories provides encapsulation change Design patterns Examples: GoF Patterns: Visitor, Strategy, Observer, ... External Polymorphism ... ## I mplementation Details How is a design implemented? Which features are used?

SFINAE • Easy to Read Error Messages • Easy to Make Custom Checks • Easy to Read Checks ## Polymorphism ## Use Case • One interface with multiple implementations • Key Object-Oriented Design method Curiously Recurring Template Pattern (CRTP) • ~1995 ## Original Trend – Virtual Functions • Run-Time Polymorphism • Quintessential Object Oriented Method • Overused ## Original Code – Virtual Functions struct // ... } }; ## New Trend – Curiously Recurring Template Pattern (CRTP) • Compile Time Polymorphism • Force a Downcast from the Parent to Access Child Elements • Explicit Cast ## New Code – CRTP

42 OOP IN PYTHON – INHERITANCE AND POLYMORPHISM ..... 44 Inheritance ..... 44 Inheriting Attributes ..... 44 Inheritance Examples ..... 45 Polymorphism (“MANY SHAPES”) ..... 47 Overriding design and build applications. Major pillars of Object Oriented Programming (OOP) are Inheritance, Polymorphism, Abstraction, and Encapsulation. Object Oriented Analysis(OOA) is the process of examining a fundamental object-oriented principles and concepts namely inheritance, abstraction, encapsulation and polymorphism.  Four Pillars

$ : $ Set_{2} $ , $ Prop_{2} $ : $ Set_{3} $ , etc. Like Set, Prop also supports universe polymorphism (see universe levels), so for each $ \ell $ : Level we have the sort Prop $ \ell $ . For example: can indeed define: Prod : List₁ Set → Set Prod [] = T Prod (A :: As) = A × Prod As ## Universe polymorphism To allow definitions of functions and datatypes that work for all possible universes $ Set_{i} of universes $ Set_{i} $ , this second hierarchy $ Set\omega_{i} $ does not support universe polymorphism. This means that it is not possible to quantify over all $ Set\omega_{i} $ at once. For example