22 General utilities library [utilities]

22.14 Formatting [format]

22.14.8 Arguments [format.arguments]

22.14.8.3 Class template basic_format_args [format.args]

namespace std { template<class Context> class basic_format_args { size_t size_; // exposition only const basic_format_arg<Context>* data_; // exposition only public: basic_format_args() noexcept; template<class... Args> basic_format_args(const format-arg-store<Context, Args...>& store) noexcept; basic_format_arg<Context> get(size_t i) const noexcept; }; template<class Context, class... Args> basic_format_args(format-arg-store<Context, Args...>) -> basic_format_args<Context>; }
An instance of basic_format_args provides access to formatting arguments.
Implementations should optimize the representation of basic_format_args for a small number of formatting arguments.
[Note 1: 
For example, by storing indices of type alternatives separately from values and packing the former.
— end note]
basic_format_args() noexcept;
Effects: Initializes size_ with 0.
template<class... Args> basic_format_args(const format-arg-store<Context, Args...>& store) noexcept;
Effects: Initializes size_ with sizeof...(Args) and data_ with store.args.data().
basic_format_arg<Context> get(size_t i) const noexcept;
Returns: i < size_ ? data_[i] : basic_format_arg<Context>().