Alias template weak_proxy
Class template weak_facade
template <facade F>
struct weak_facade; // since 3.3.0
template <facade F>
using weak_proxy = proxy<weak_facade<F>>; // since 3.3.0
Class template weak_facade is a facade type for weak pointers (e.g., std::weak_ptr) potentially converted from a proxy object.
Member Types of observer_facade
| Name |
Description |
convention_types |
A tuple-like type that contains one convention type C, whereC::is_direct is false, C::dispatch_type is of member function lock with accessibility, and C::overload_types is a tuple-like type that contains type proxy<F>() const noexcept. |
reflection_types |
A tuple-like type that contains no types. |
Member Constants of observer_facade
| Name |
Description |
constraints [static] [constexpr] |
Equivalent to F::constraints |
Example
#include <iostream>
#include "proxy.h"
struct Formattable : pro::facade_builder
::support_format
::build {};
int main() {
std::shared_ptr<int> val = std::make_shared<int>(123);
pro::weak_proxy<Formattable> wp = std::weak_ptr{val};
pro::proxy<Formattable> p = wp.lock();
std::cout << std::boolalpha << p.has_value() << "\n"; // Prints "true"
std::cout << std::format("{}\n", *p); // Prints "123"
p.reset();
val.reset();
p = wp.lock();
std::cout << p.has_value() << "\n"; // Prints "false"
}
See Also