Class substitution_dispatch
Header:
proxy.h
Module:proxy
Namespace:pro::inline v4
Since: 4.0.1
class substitution_dispatch;
Class substitution_dispatch models a dispatch type for proxy substitution. It meets the ProAccessible requirements of applicable types.
Member Functions
| Name | Description |
|---|---|
| (constructor) [nothrow] | constructs an substitution_dispatch object |
operator() |
invokes the dispatch |
Member Types
| Name | Description |
|---|---|
accessor |
provides accessibility to proxy |
Example
#include <iostream>
#include <proxy/proxy.h>
struct Runnable : pro::facade_builder //
::add_convention<pro::operator_dispatch<"()">, void()> //
::build {};
struct CopyableRunnable : pro::facade_builder //
::support_copy<pro::constraint_level::nontrivial> //
::add_facade<Runnable> //
::add_direct_convention<pro::substitution_dispatch,
pro::proxy<Runnable>() const&,
pro::proxy<Runnable>() &&> //
::build {};
int main() {
pro::proxy<CopyableRunnable> p1 = pro::make_proxy<CopyableRunnable>(
[] { std::cout << "Lambda expression invoked\n"; });
// Implicit conversion via const reference of pro::proxy<CopyableRunnable>
pro::proxy<Runnable> p2 = p1;
std::cout << std::boolalpha << p2.has_value() << "\n"; // Prints "true"
// Implicit conversion via rvalue reference of pro::proxy<CopyableRunnable>
pro::proxy<Runnable> p3 = std::move(p1);
std::cout << p1.has_value() << "\n"; // Prints "false"
(*p3)(); // Prints "Lambda expression invoked"
// Different from implicit_conversion_dispatch, substitution from a null proxy
// is well-formed
pro::proxy<Runnable> p4 = p1;
std::cout << p4.has_value() << "\n"; // Prints "false"
}