Important Notes

• decltype inspects types without evaluating expressions; parentheses affect results.

• auto may drop top-level const and references; use decltype(auto) to preserve.

• constexpr shifts pure computation to compile time.

• inline helps with ODR when defining functions in headers.

• noexcept conveys and enforces exception guarantees; use deliberately.

• std::function provides flexibility at a runtime cost—choose it when needed.