kind of awkward, but maybe there is no other way..

src/core/event_man.rs

@@ -1,5 +1,4 @@
 use std::collections::HashMap;
-use std::sync::mpsc::{Receiver, Sender};
 use crate::core::events::{Event, EventRaw, GroupId};
 
 #[derive(PartialEq, Eq, Hash, Copy, Clone)]
@@ -8,60 +7,74 @@ enum ListenerType {
     Group(GroupId),
 }
 
-struct Listener {
+pub trait EventRecipient {
+    type Error;
+    fn send_to(&mut self, event: Event) -> Result<(), Self::Error>;
+}
+
+struct Listener<E> {
     _ltype: ListenerType,
-    dest: Sender<Event>,
+    dest: Box<dyn EventRecipient<Error=E>>,
 }
 
-pub struct EventManager {
-    listeners: HashMap<ListenerType, Vec<Listener>>,
-    event_receiver: Receiver<Event>,
+pub trait ReceivesEvent {
+    fn receive(&mut self) -> Option<Event>;
 }
 
-impl EventManager {
-    pub fn subcribe_single(&mut self, event: Event, dest: Sender<Event>) {
+
+pub struct EventManager<E> {
+    listeners: HashMap<ListenerType, Vec<Listener<E>>>,
+    event_receiver: dyn ReceivesEvent,
+}
+
+impl<E> EventManager<E> {
+    pub fn subcribe_single(&mut self, event: Event, dest: impl EventRecipient<Error=E> + 'static) {
         self.update_listeners(ListenerType::Single(event.raw()), dest);
     }
 
-    pub fn subscribe_group(&mut self, group_id: GroupId, dest: Sender<Event>) {
+    pub fn subscribe_group(&mut self, group_id: GroupId, dest: impl EventRecipient<Error=E> + 'static) {
         self.update_listeners(ListenerType::Group(group_id), dest);
     }
 
-    fn update_listeners(&mut self, key: ListenerType, dest: Sender<Event>) {
-        if let std::collections::hash_map::Entry::Vacant(e) = self.listeners.entry(key) {
-            e.insert(vec![Listener { _ltype: key, dest }]);
+    fn update_listeners (&mut self, key: ListenerType, dest: impl EventRecipient<Error=E> + 'static) {
+        if !self.listeners.contains_key(&key) {
+            self.listeners.insert(key, vec![Listener { _ltype: key, dest: Box::new(dest) }]);
         } else {
             let vec = self.listeners.get_mut(&key).unwrap();
-            vec.push(Listener { _ltype: key, dest });
+            vec.push(Listener { _ltype: key, dest: Box::new(dest) });
         }
     }
 
-    pub fn periodic_op(&mut self) {
-        if let Ok(event) = self.event_receiver.recv() {
+    pub fn periodic_op(&mut self) -> Result<(), E> {
+        if let Some(event) = self.event_receiver.receive() {
             println!("Received event {:?}", event);
-            for (ltype, listener_list) in self.listeners.iter() {
+            for (ltype, listener_list) in self.listeners.iter_mut() {
                 match ltype {
                     ListenerType::Single(raw_event) => {
                         if event.raw() == *raw_event {
-                            for listener in listener_list {
-                                listener.dest.send(event).expect("Sending event failed");
+                            for listener in listener_list.iter_mut() {
+                                listener.dest.send_to(event)?;
                             }
                         }
                     }
                     ListenerType::Group(group_id) => {
                         if event.group_id() == *group_id {
-                            for listener in listener_list {
-                                listener.dest.send(event).expect("Sending event failed");
+                            for listener in listener_list.iter_mut() {
+                                listener.dest.send_to(event)?;
                             }
                         }
                     }
                 }
             }
         }
+        Ok(())
     }
 }
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn basic_test() {
 
+    }
 }