- `=delete` can be used to prevent calling the wrong overload
- C++20 `[[nodiscard("reason")]]`
- This issues a warning if the return value of a function is discarded (not handled), which is good for ensuring error handling.
- C++17 for the entire class/struct
- C++20 for constructors
- C++23 for lambdas
- The compiler injects `operator()` in the code of the destination function and then compile the routine. Operator inlining is the standard behavior
- C++11 lambda expression: capture clause
- `[]` captures nothing
- `[&]` captures all variables by reference
- `[=]` captures all variables by value
- `[=, x, &y]` captures `x` by value and `y` by reference, all other variables by value
- C++17 `[this]` captures the current object by reference
- C++14 `[x=x]`, `[&x=x]` capture current object member `x` by value/reference
- C++20 deprecates `[=]` capturing `this` pointer by value
- C++14 `[](auto value)`, `[](int i = 6)`
- A function can return a lambda (dynamic dispatch is also possible)
- C++17 `constexpr` lambda, C++20 `consteval` lambda, `mutable`
- syntax: post specifier
- C++20 `template` and `requires` clause for lambda
auto lambda = []<typename T>(T value)
requires std::is_arithmetic_v<T> {
return value * 2;
};
auto v = lambda(3.4); // v: 6.8 (double)
struct A{} a;
// auto v = lambda(a); // compiler error
- When Preprocessors are Necessary
- Conditional compiling
- [Abseil Platform Check Macros](https://abseil.io/docs/cpp/platforms/macros)
- Mixing different languages
- Complex name replacing
- [Are We Macro free Yet, CppCon2019](https://github.com/CppCon/CppCon2019/blob/master/Presentations/are_we_macrofree_yet/are_we_macrofree_yet__zhihao_yuan__cppcon_2019.pdf)
- C++20 `<source location>`
- replaces `__FILE__`, `__LINE__`, C++11 `__func__`
- still: non-standard `__PRETTY_FUNCTION__`
- C++17 [`__has_include`](https://en.cppreference.com/w/cpp/preprocessor/include)
- stringizing macro operator `#`, e.g. `#string` expands to `"string"`
- token pasting macro operator `##`, e.g. `x##y` expands to `xy`
- `#error`, C++23 `#warning`
- non-portable `pragma`, C++11 `_Pragma`
- C++11 `__VA_ARGS__`