dpp::event_router_t< T > Class Template Reference

Handles routing of an event to multiple listeners. More...

#include <cluster.h>

Public Member Functions
	event_router_t ()
	Construct a new event_router_t object. More...
void	call (const T &event) const
	Call all attached listeners. Listenrs may cancel, by calling the event.cancel method. More...
bool	empty () const
	Returns true if the container of listeners is empty, i.e. there is nothing listening for this event right now. More...
	operator bool () const
	Returns true if any listeners are attached. More...
event_handle	operator() (std::function< void(const T &)> func)
	Attach a lambda to the event, adding a listener. The lambda should follow the signature specified when declaring the event object and should take exactly one parameter derived from event_dispatch_t. More...
event_handle	attach (std::function< void(const T &)> func)
	Attach a lambda to the event, adding a listener. The lambda should follow the signature specified when declaring the event object and should take exactly one parameter derived from event_dispatch_t. More...
bool	detach (const event_handle &handle)
	Detach a listener from the event using a previously obtained ID. More...

Detailed Description

template<class T>
class dpp::event_router_t< T >

Handles routing of an event to multiple listeners.

Multiple listeners may attach to the event_router_t by means of operator(). Passing a lambda into operator() attaches to the event.

Dispatchers of the event may call the event_router_t::call() method to cause all listeners to receive the event.

The event_router_t::empty() method will return true if there are no listeners attached to the event_router_t (this can be used to save time by not constructing objects that nobody will ever see).

The event_router_t::detach() method removes an existing listener from the event, using the event_handle ID returned by operator().

This class is used by the library to route all websocket events to listening code.

Example:

// Declare an event that takes log_t as its parameter
event_router_t<log_t> my_event;
 
// Attach a listener to the event
event_handle id = my_event([&](const log_t& cc) {
    std::cout << cc.message << "\n";
});
 
// Construct a log_t and call the event (listeners will receive the log_t object)
log_t lt;
lt.message = "foo";
my_event.call(lt);
 
// Detach from an event using the handle returned by operator()
my_event.detach(id);

Template Parameters

T	type of single parameter passed to event lambda derived from event_dispatch_t

Constructor & Destructor Documentation

event_router_t()

template<class T >

dpp::event_router_t< T >::event_router_t ( )

inline

Construct a new event_router_t object.

Member Function Documentation

attach()

template<class T >

event_handle dpp::event_router_t< T >::attach ( std::function< void(const T &)>  func )

inline

Attach a lambda to the event, adding a listener. The lambda should follow the signature specified when declaring the event object and should take exactly one parameter derived from event_dispatch_t.

Parameters

func	Function lambda to attach to event

Returns

event_handle An event handle unique to this event, used to detach the listener from the event later if necessary.

call()

template<class T >

void dpp::event_router_t< T >::call ( const T &  event ) const

inline

Call all attached listeners. Listenrs may cancel, by calling the event.cancel method.

Parameters

event

Class to pass as parameter to all listeners.

detach()

template<class T >

bool dpp::event_router_t< T >::detach ( const event_handle &  handle )

inline

Detach a listener from the event using a previously obtained ID.

Parameters

handle

An ID obtained from event_router_t::operator()

Returns

true The event was successfully detached

false The ID is invalid (possibly already detached, or does not exist)

empty()

template<class T >

bool dpp::event_router_t< T >::empty ( ) const

inline

Returns true if the container of listeners is empty, i.e. there is nothing listening for this event right now.

Returns

true if there are no listeners

false if there are some listeners

operator bool()

template<class T >

dpp::event_router_t< T >::operator bool ( ) const

inline

Returns true if any listeners are attached.

This is the boolean opposite of event_router_t::empty().

Returns

true if listeners are attached

false if no listeners are attached

operator()()

template<class T >

event_handle dpp::event_router_t< T >::operator() ( std::function< void(const T &)>  func )

inline

Attach a lambda to the event, adding a listener. The lambda should follow the signature specified when declaring the event object and should take exactly one parameter derived from event_dispatch_t.

Parameters

func	Function lambda to attach to event

Returns

event_handle An event handle unique to this event, used to detach the listener from the event later if necessary.