Modern Idioms That Pay Rent

Modern C++ is mostly removing footguns. Four idioms pay rent immediately.

1. Narrow interfaces with types. A std::string_view parameter accepts std::string, a literal, or a slice without copying:

#include <string_view>

bool is_command(std::string_view s) {
    return s.starts_with("--");   // C++20
}

Views do not own; they must not outlive the underlying string.

2. Structured bindings for pair/tuple/struct unpacking — for (const auto& [k, v] : map) beats .first/.second for readability.

3. constexpr for tables and limits — magic numbers move to named, compile-time-checked constants.

4. Exhaustive switch over enum class with no default — the compiler then forces you to update every switch when the enum grows. That is free maintenance.

And one deprecation to know: std::auto_ptr and throwing std::vector::operator[] are history; dynamic exception specifications (throw(...)) are gone from the language. Modern code catches specific exception types — Module 10's job.