PRO_DEF_FREE_DISPATCH#define PRO_DEF_FREE_DISPATCH // see below
Macro PRO_DEF_FREE_DISPATCH defines dispatch types for free function expressions with accessibility. It supports two syntaxes:
// (1)
PRO_DEF_FREE_DISPATCH(dispatch_name, func_name);
// (2)
PRO_DEF_FREE_DISPATCH(dispatch_name, func_name, accessibility_func_name);
(1) Equivalent to PRO_DEF_FREE_DISPATCH(dispatch_name, func_name, func_name);
(2) Defines a class named dispatch_name of free function call expressions of func_name with accessibility. dispatch_name meets the ProAccessible requirements of types F, C, and Os..., where F models concept facade, C is a tuple element type defined in typename F::convention_types, and each type O (possibly qualified with cv ref noex) in Os... is a tuple element type defined in typename C::overload_types. The functions provided by typename dispatch_name::template accessor<F, C, Os...> are named accessibility_func_name and can be found by argument-dependent lookup when accessor is an associated class of the arguments. Let SELF be std::forward<accessor cv ref>(self), effectively equivalent to:
struct dispatch_name {
template <class T, class... Args>
decltype(auto) operator()(T&& self, Args&&... args)
noexcept(noexcept(func_name(std::forward<T>(self), std::forward<Args>(args)...)))
requires(requires { func_name(std::forward<T>(self), std::forward<Args>(args)...); }) {
return func_name(std::forward<T>(self), std::forward<Args>(args)...);
}
template <class F, class C, class... Os> struct accessor {
accessor() = delete;
};
template <class F, class C, class... Os>
requires(sizeof...(Os) > 1u && (std::is_trivial_v<accessor<F, C, Os>> && ...))
struct accessor<F, C, Os...> : accessor<F, C, Os>... {};
template <class F, class C, class R, class... Args>
struct accessor<F, C, R(Args...) cv ref noex> {
friend R accessibility_func_name(accessor cv ref self, Args... args) noex {
return pro::proxy_invoke<C, R(Args...) cv ref noex>(pro::access_proxy<F>(SELF), std::forward<Args>(args)...);
}
};
};
#include <iostream>
#include <string>
#include "proxy.h"
PRO_DEF_FREE_DISPATCH(FreeToString, std::to_string, ToString);
struct Stringable : pro::facade_builder
::add_convention<FreeToString, std::string()>
::build {};
int main() {
pro::proxy<Stringable> p = pro::make_proxy<Stringable>(123);
std::cout << ToString(*p) << "\n"; // Prints: "123"
}