The C++ Type System Is Your Friend

This talk shows how C++ types and templates can support safe, generic, reusable code through lightweight abstractions. It covers domain types, value validation, policies, and compile-time checks, aiming to improve readability and prevent errors without run-time overhead.

Syllabus

Intro
Safe, performant, reusable code
(Mostly) typeless programming
Machine-typed programming
Type-rich programming
The miracle of compilation Runtime
Physical types
Whole Value pattern
Templates to the rescue
Adding checking of values
Reuse through client libraries
Physical quantities and dimensions
Tailoring operations - library code
Tailoring operations - client code
Templates and policies
Implementing policies • Let's use a policy on overflow
Constructor validation logic • Let's use a policy to enforce that quantities are non-negative
Effect of constructor validation logic . So, what about the generated code?
Starting to define a domain type . We have now restricted both the operations and the range of allowed values
Domain types vs primitives • Business rules still exist when using primitives: they are just distributed
Compile-time range calculation
Scaling and errors • As systems get larger the number of possible combinations of types (and therefore incompatibilities) grows even faster
Templates and "concepts lite"
Concepts code - first attempt