make_proxy_observed.md

Function template make_proxy_observed

Header: proxy.h
Module: proxy
Namespace: pro::inline v4
Since: 4.1.0

The definition of make_proxy_observed makes use of an exposition-only class template observer-ptr. observer-ptr<T> contains a raw pointer to an object of type T, and provides operator* for access with the same qualifiers.

template <facade F, class T>
proxy<F> make_proxy_observed(T& value) noexcept;

Creates a proxy<F> object containing a value p of type observer-ptr<T>, where *p is direct-non-list-initialized with std::addressof(value). If proxiable_target<T, F> is false, the program is ill-formed and diagnostic messages are generated.

Return Value

The constructed proxy object.

Example

#include <iostream>

#include <proxy/proxy.h>

struct Printable : pro::facade_builder //
                   ::add_convention<pro::operator_dispatch<"<<", true>,
                                    std::ostream&(std::ostream&) const> //
                   ::build {};

int main() {
  int val = 123;
  pro::proxy<Printable> p = pro::make_proxy_observed<Printable>(val);

  // Prints "123"
  std::cout << *p << "\n";

  val = 456;

  // Prints "456"
  std::cout << *p << "\n";
}

See Also

• concept proxiable_target
• function template make_proxy_view