cpp-templates-metaprogramming

Use C++20 concepts with a requires clause or the abbreviated template syntax to constrain template parameters. For older standards, use std::enable_if with type traits like std::is_integral to enable overloads only for matching types.

SFINAE removes invalid template overloads from consideration using substitution failure, typically via std::enable_if. Concepts express constraints directly and produce clearer compiler error messages, making them the preferred approach in C++20.

Variadic templates accept parameter packs of any size using typename... Args. C++17 fold expressions like (args + ...) expand the pack with an operator, replacing recursive template instantiation for operations like summing all arguments.

Prefer constexpr functions for compile-time computation because they are more readable and debuggable than recursive template structs. Reserve template metaprogramming for type-level operations like type lists and trait manipulation.

Template errors cascade through every instantiation layer, and the compiler reports the full substitution chain. Using concepts, static_assert with clear messages, and if constexpr reduces error depth and points directly to the violated constraint.

CRTP (Curiously Recurring Template Pattern) passes the derived class as a template parameter to its base, enabling static polymorphism resolved at compile time. Use it to avoid virtual function overhead in performance-critical code.