Installs a handler into the slot.

template<
    typename CancellationHandler>
decay_t< CancellationHandler > & assign(
    CancellationHandler && handler);

Destroys any existing handler in the slot, then installs the new handler, constructing it as a decay-copy of the supplied handler.

The handler is a function object to be called when the signal is emitted. The signature of the handler must be

void handler(boost::asio::cancellation_type_t);

Parameters

Return Value

A reference to the newly installed handler.