Matching

Classes related to getting information about matching Zenoh entities.

struct MatchingStatus

A struct that indicates if there exist Subscribers matching the Publisher’s key expression or Queryables matching Querier’s key expression and target.

Fields

bool matching

true if there exist entities matching the target (i.e either Subscribers matching Publisher’s key expression or Queryables matching Querier’s key expression and target).

template<class Handler>
class MatchingListener : public zenoh::detail::MatchingListenerBase

A Zenoh matching listener.

A listener that sends notifications when the [MatchingStatus] of a corresponding Zenoh entity changes. Dropping the corresponding Zenoh entity, disables the matching listener.

Methods

inline Handler undeclare(ZResult *err = nullptr) &&

Undeclare matching listener, and return its handler, which can still be used to process any messages received prior to undeclaration.

Parameters:

err – if not null, the result code will be written to this location, otherwise ZException exception will be thrown in case of error.

inline const Handler &handler() const

Return the handler to matching listener data stream.

Constructors

inline MatchingListener(MatchingListener<void> &&m, Handler handler)

Construct stream matching listener from callback matching listener and handler.

Parameters:

• m – callback matching listener, that should expose data to the handler in its callback.

• handler – handler to access data exposed by m. Zenoh handlers implement recv and try_recv methods, for blocking and non-blocking message reception. But user is free to define his own interface.