Design Pattern Note

Design patterns

• Are about dependencies and abstractions
• Are about intent
• Are not limited to OO programming
• Are not limited to dynamic polymorphism
• Are not outdated nor obsolete
• Are everywhere

C++ STL examples

Strategy

• std::accumulate

Command

• std::for_each
• std::transform

Iterator

• Iterator library

Adapter

• std::queue
• std::stack
• std::priority_queue

Decorator

• std::pmr::monotonic_buffer_resource

Template Method

• std::pmr::memory_resource

Proxy

• std::vector< bool >
• std::bitset

External Polymorphism

• Concepts library

Bridge

• PIMPL

Prototype

• virtual std::unique<Concept> clone() const = 0

Type erasure

• Templated constructor
• Completely non-virtual interface
• External Polymorphism + Bridge + Prototype

Reference

• Klaus Iglberger - Design Patterns - Facts and Misconceptions
• Design Patterns: Facts and Misconceptions - Klaus Iglberger - CppCon 2021