From 6f3db18146cf168c01836f57f05e633cb1a750a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krist=C3=B3f=20T=C3=B3th?= <kristof.toth@avatao.com>
Date: Fri, 1 Jun 2018 14:21:32 +0200
Subject: [PATCH] Use power of LazyInitialise to replace
 CallbackMixin.__init__()

---
 lib/tfw/components/history_monitor.py | 1 -
 lib/tfw/fsm_base.py                   | 1 -
 lib/tfw/mixins/callback_mixin.py      | 7 +++++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/tfw/components/history_monitor.py b/lib/tfw/components/history_monitor.py
index 67bfc3b..b103bb9 100644
--- a/lib/tfw/components/history_monitor.py
+++ b/lib/tfw/components/history_monitor.py
@@ -36,7 +36,6 @@ class HistoryMonitor(CallbackMixin, ObserverMixin, ABC):
     See examples below.
     """
     def __init__(self, histfile):
-        CallbackMixin.__init__(self)
         self.histfile = histfile
         self._history = []
         self._last_length = len(self._history)
diff --git a/lib/tfw/fsm_base.py b/lib/tfw/fsm_base.py
index d2e1df0..85ac12f 100644
--- a/lib/tfw/fsm_base.py
+++ b/lib/tfw/fsm_base.py
@@ -19,7 +19,6 @@ class FSMBase(CallbackMixin):
     states, transitions = [], []
 
     def __init__(self, initial: str = None, accepted_states: List[str] = None):
-        CallbackMixin.__init__(self)
         self.accepted_states = accepted_states or [self.states[-1]]
         self.machine = Machine(model=self,
                                states=self.states,
diff --git a/lib/tfw/mixins/callback_mixin.py b/lib/tfw/mixins/callback_mixin.py
index e5cd534..971de5c 100644
--- a/lib/tfw/mixins/callback_mixin.py
+++ b/lib/tfw/mixins/callback_mixin.py
@@ -3,10 +3,13 @@
 
 from functools import partial
 
+from tfw.decorators import LazyInitialise
+
 
 class CallbackMixin:
-    def __init__(self):
-        self._callbacks = []
+    @LazyInitialise
+    def _callbacks(self):
+        return []
 
     def subscribe_callback(self, callback, *args, **kwargs):
         """