From 0711c9beba4bc10fcae2c8365351db3241564aa5 Mon Sep 17 00:00:00 2001
From: bitfl0wer <florian@pro-weber.com>
Date: Thu, 27 Apr 2023 22:38:41 +0200
Subject: [PATCH] Indicate that method call can fail

---
 src/gateway.rs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/gateway.rs b/src/gateway.rs
index 7206c4e..9a05fec 100644
--- a/src/gateway.rs
+++ b/src/gateway.rs
@@ -1,3 +1,5 @@
+use crate::errors::ObserverError;
+
 #[derive(Debug)]
 pub struct Gateway {}
 
@@ -24,12 +26,13 @@ impl<'a> GatewayEvent<'a> {
         self.is_observed
     }
 
-    pub fn subscribe(&mut self, observable: &'a dyn Observer) {
+    pub fn subscribe(&mut self, observable: &'a dyn Observer) -> Option<ObserverError> {
         if self.is_observed {
-            return;
+            return Some(ObserverError::AlreadySubscribedError);
         }
         self.is_observed = true;
-        self.observers.push(observable)
+        self.observers.push(observable);
+        None
     }
 
     pub fn unsubscribe(&mut self, observable: &'a dyn Observer) {