basic_facade_builder::support_viewusing support_view = basic_facade_builder</* see below */>;
The member type support_view of basic_facade_builder<Cs, Rs, C> adds necessary convention types to allow implicit conversion from proxy<F> to proxy_view<F> where F is a facade type built from basic_facade_builder.
Let p be a value of type proxy<F>, ptr be the contained value of p (if any), the conversion from type proxy<F>& to type proxy_view<F> is equivalent to return raw-ptr{std::addressof(*ptr)} if p contains a value, or otherwise equivalent to return nullptr. observer-ptr is an exposition-only type that *observer-ptr, *std::as_const(observer-ptr), *std::move(observer-ptr) and *std::move(std::as_const(observer-ptr)) are equivalent to *ptr, *std::as_const(ptr), *std::move(ptr) and *std::move(std::as_const(ptr)), respectively.
support_view is useful when a certain context does not take ownership of a proxy object. Similar to std::unique_ptr::get, std::shared_ptr::get and the borrowing mechanism in Rust.
#include <iostream>
#include "proxy.h"
struct RttiAware : pro::facade_builder
::support_rtti
::support_view
::build {};
int main() {
pro::proxy<RttiAware> p = pro::make_proxy<RttiAware>(123);
pro::proxy_view<RttiAware> pv = p;
proxy_cast<int&>(*pv) = 456; // Modifies the contained object of p
std::cout << proxy_cast<int>(*pv) << "\n"; // Prints "456"
std::cout << proxy_cast<int>(*p) << "\n"; // Prints "456"
}