C++ named requirements: Formatter (od C++20)
Formatter is a type that abstracts formatting operations for a given formatting argument type and character type. Specializations of std::formatter provided by the standard library are required to meet the requirements of Formatter except as noted otherwise.
A Formatter is able to format both const and non-const arguments, typically by providing a format member function that takes a const reference.
Requirements
A type satisfies Formatter if it satisfies BasicFormatter and given
Arg
, a formatting argument typeCharT
, a character typeFormatter
, a Formatter type for types Arg and CharTOutputIt
, a LegacyOutputIterator typef
, a value of type (possibly const) Formatterg
, a value of type Formatterarg
, an lvalue of type Argt
, a value of type convertible to (possibly const) ArgParseContext
, an alias ofstd::basic_format_parse_context<CharT>
FormatContext
, an alias ofstd::basic_format_context<OutputIt, CharT>
parse_ctx
, an lvalue of type ParseContextformat_ctx
, an lvalue of type FormatContext
Expression | Return type | Semantics |
---|---|---|
f.format(t, format_ctx) | FormatContext::iterator | * Formats t according to the specifiers stored in f , writes the output to format_ctx.out() and returns an end iterator of the output range.* The output shall only depend on * t ,* format_ctx.locale() , * the range [parse_ctx.begin(), parse_ctx.end()) from the last call to f.parse(parse_ctx) , and * format_ctx.arg(n) for any value n of type std::size_t. |
f.format(arg, format_ctx) | FormatContext::iterator | As above, but does not modify arg . |