C++ Software Design

Chapter 8. The Type Erasure Design Pattern

Separation of concerns and value semantics are two of the essential takeaways from this book that I have mentioned a couple of times by now. In this chapter, these two are beautifully combined into one of the most interesting modern C++ design patterns: Type Erasure. Since this pattern can be considered one of the hottest irons in the fire, in this chapter I will give you a very thorough, in-depth introduction to all aspects of Type Erasure. This, of course, includes all design-specific aspects and a lot of specifics about implementation details.

In “Guideline 32: Consider Replacing Inheritance Hierarchies with Type Erasure”, I will introduce you to Type Erasure and give you an idea why this design pattern is such a great combination of dependency reduction and value semantics. I will also give you a walkthrough of a basic, owning Type Erasure implementation.

“Guideline 33: Be Aware of the Optimization Potential of Type Erasure” is an exception: despite the fact that in this book I primarily focus on dependencies and design aspects, in this one guideline I will entirely focus on performance-related implementation details. I will show you how to apply the Small Buffer Optimization (SBO) and how to implement a manual virtual dispatch to speed up your Type Erasure implementation.

In “Guideline 34: Be Aware of the Setup Costs of Owning Type Erasure Wrappers”, we will investigate the setup costs of the owning Type Erasure implementation. We ...