proxy

Macro `PRO_DEF_FREE_AS_MEM_DISPATCH`

#define PRO_DEF_FREE_AS_MEM_DISPATCH // see below

Macro PRO_DEF_FREE_AS_MEM_DISPATCH defines dispatch types for free function expressions with accessibility via a member function. It supports two syntaxes:

// (1)
PRO_DEF_FREE_AS_MEM_DISPATCH(dispatch_name, func_name);

// (2)
PRO_DEF_FREE_AS_MEM_DISPATCH(dispatch_name, func_name, accessibility_func_name);

(1) Equivalent to PRO_DEF_FREE_AS_MEM_DISPATCH(dispatch_name, func_name, func_name);

(2) Defines a class named dispatch_name of free function call expressions of func_name with accessibility via a member function. 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 member functions provided by typename dispatch_name::template accessor<F, C, Os...> are named accessibility_func_name. Let SELF be std::forward<accessor cv ref>(*this), 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>... {
    using accessor<F, C, Os>::accessibility_func_name ...;
  };
  template <class F, class C, class R, class... Args>
  struct accessor<F, C, R(Args...) cv ref noex> {
    R accessibility_func_name(Args... args) cv ref noex {
      return pro::proxy_invoke<C, R(Args...) cv ref noex>(pro::access_proxy<F>(SELF), std::forward<Args>(args)...);
    }
  };
}

Example

#include <iostream>
#include <string>

#include "proxy.h"

PRO_DEF_FREE_AS_MEM_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 << p->ToString() << "\n";  // Prints: "123"
}

proxy

Macro PRO_DEF_FREE_AS_MEM_DISPATCH

Example

See Also

Macro `PRO_DEF_FREE_AS_MEM_DISPATCH`