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Alias template fmt_format
Alias template fmt_wformat

Header: proxy_fmt.h
Module: None
Namespace: pro::inline v4::skills
Since: 4.0.0

template <class FB>
using fmt_format = /* see below */;

template <class FB>
using fmt_wformat = /* see below */;

The alias templates fmt_format and fmt_wformat modify a specialization of basic_facade_builder to allow formatting via the {fmt} library. Specializations of fmt::formatter<proxy_indirect_accessor<F>, char> and fmt::formatter<proxy_indirect_accessor<F>, wchar_t> will be enabled for the 2 skills, respectively, where F is a built facade type.

fmt_format and fmt_wformat also add constraints to a built facade type F, requiring a contained value of proxy<F> be formattable. Formally, let p be a contained value of proxy<F>, CharT be char (for format) or wchar_t (for wformat), T be std::decay_t<decltype(*std::as_const(p))>, fmt::formatter<T, CharT> shall be an enabled specialization of fmt::formatter.

Notes

This facility requires the {fmt} library to be properly installed and included before including proxy_fmt.h.

  • The minimum required version of {fmt} is 6.1.0.
  • If you are using {fmt} version 8.0.0 or newer, you must also include the header fmt/xchar.h.
  • When using modules, ensure that the macro FMT_VERSION is predefined.

Example

#include <iostream>

#include <fmt/format.h>
#include <fmt/xchar.h>
#include <proxy/proxy.h>
#include <proxy/proxy_fmt.h>

struct Formattable : pro::facade_builder                  //
                     ::add_skill<pro::skills::fmt_format> //
                     ::build {};

int main() {
  pro::proxy<Formattable> p = pro::make_proxy<Formattable>(3.14159);
  std::cout << fmt::format("*p = {:.2f}\n", *p); // Prints "*p = 3.14"
}

See Also