std::execution:: read_env

A sender factory that returns a sender that reaches into a receiver’s environment and pulls out the current value associated with a given query object .

For any query object q , the expression read_env ( q ) is expression-equivalent to /*make-sender*/ ( read_env, q ) .

Customization point objects

The name execution::read_env denotes a customization point object , which is a const function object of a literal semiregular class type. See CustomizationPointObject for details.

Example

An example usage of this factory is to schedule dependent work on the receiver's scheduler, which can be obtained with read_env ( get_scheduler ) :

std::execution::sender auto task =
  std::execution::read_env(std::execution::get_scheduler)
    | std::execution::let_value([](auto sched) {
        return std::execution::starts_on(sched, /*some nested work here*/);
    });
std::this_thread::sync_wait( std::move(task) ); // wait for it to finish