Struct telegram_bot::Listener

pub struct Listener { /* fields omitted */ }

Offers methods to easily receive new updates via the specified method. This should be used instead of calling methods like get_updates yourself.

To create a listener, you first have to create an Api object and call listener on it. In order to make listening easier in a concurrent environment, the Listener object and the Api object don't share any internal state. This makes creating a Listener a bit more expensive, but it's usually sufficient for any purpose to create a Listener only once.

Methods

impl Listener

pub fn listen<H>(&mut self, handler: H) -> Result<()> where     H: FnMut(Update) -> Result<ListeningAction>,

Receive and handle updates with the given closure.

This method will use the specified listening method to receive new updates and will then call the given handler for every update. Normally the handler won't ever be called for the same update twice (see Note below). When the handler returns an Err value, this function will stop listening and return the same Err. If you want to stop listening you can return Ok(ListeningAction::Stop) instead of an Err value.

When returning an Ok value, the update that was passed to the handler is considered handled and won't be passed to a handler again. On the other hand if an Err is returned, the update is not considered handled so it will be passed to a handler the next time again.

Note: If you are listening via LongPoll method and your handler panics or the program is aborted in an abnormal way (e.g. SIGKILL), the handler might receive some already handled updates a second time.

pub fn channel(self) -> (Sender<Result<ListeningAction>>, Receiver<Update>)

Consumes self and returns a sender-receiver pair. You can receive new updates through the Receiver. Each update needs to be confirmed with a Result<ListeningAction> before the next update can be handled.

This means that handling updates isn't done in parallel. The only advantage of this function over the listen function is that you can ask the receiver, if a new update has arrived. This is useful if you want to handle different events in one thread. E.g. a remainder bot gets active on every received message AND on timed events.

Note: Remember to send a result through the Sender after each update!