serve-robotics
diff --git a/‎examples/browser.py
Copy file name to clipboardExpand all lines: examples/browser.py
+7-12Lines changed: 7 additions & 12 deletions b/‎examples/browser.py
Copy file name to clipboardExpand all lines: examples/browser.py
+7-12Lines changed: 7 additions & 12 deletions
diff --git a/‎zeroconf.py
Copy file name to clipboardExpand all lines: zeroconf.py
+56-8Lines changed: 56 additions & 8 deletions b/‎zeroconf.py
Copy file name to clipboardExpand all lines: zeroconf.py
+56-8Lines changed: 56 additions & 8 deletions
@@ -7,19 +7,14 @@
 import socket
 from time import sleep
 
-from zeroconf import ServiceBrowser, Zeroconf
+from zeroconf import ServiceBrowser, ServiceStateChange, Zeroconf
 
 
-class MyListener(object):
+def on_service_state_change(zeroconf, service_type, name, state_change):
+    print("Service %s of type %s state changed: %s" % (name, service_type, state_change))
 
-    def remove_service(self, zeroconf, type, name):
-        print("Service %s removed" % (name,))
-        print('\n')
-
-    def add_service(self, zeroconf, type, name):
-        print("Service %s added" % (name,))
-        print("  Type is %s" % (type,))
-        info = zeroconf.get_service_info(type, name)
+    if state_change is ServiceStateChange.Added:
+        info = zeroconf.get_service_info(service_type, name)
         if info:
             print("  Address is %s:%d" % (socket.inet_ntoa(info.address),
                                           info.port))
@@ -40,8 +35,8 @@ def add_service(self, zeroconf, type, name):
 
     zeroconf = Zeroconf()
     print("\nBrowsing services, press Ctrl-C to exit...\n")
-    listener = MyListener()
-    browser = ServiceBrowser(zeroconf, "_http._tcp.local.", listener)
+    browser = ServiceBrowser(zeroconf, "_http._tcp.local.", handlers=[on_service_state_change])
+
     try:
         while True:
             sleep(0.1)
 
@@ -53,7 +53,7 @@ def emit(self, record):
 
 __all__ = [
     "Zeroconf", "ServiceInfo", "ServiceBrowser",
-    "Error", "InterfaceChoice",
+    "Error", "InterfaceChoice", "ServiceStateChange",
 ]
 
 
@@ -921,6 +921,33 @@ def run(self):
                     self.zc.cache.remove(record)
 
 
+class Signal(object):
+    def __init__(self):
+        self._handlers = []
+
+    def fire(self, **kwargs):
+        for h in list(self._handlers):
+            h(**kwargs)
+
+    @property
+    def registration_interface(self):
+        return SignalRegistrationInterface(self._handlers)
+
+
+class SignalRegistrationInterface(object):
+
+    def __init__(self, handlers):
+        self._handlers = handlers
+
+    def register_handler(self, handler):
+        self._handlers.append(handler)
+        return self
+
+    def unregister_handler(self, handler):
+        self._handlers.remove(handler)
+        return self
+
+
 class ServiceBrowser(threading.Thread):
 
     """Used to browse for a service of a specific type.
@@ -929,13 +956,12 @@ class ServiceBrowser(threading.Thread):
     remove_service() methods called when this browser
     discovers changes in the services availability."""
 
-    def __init__(self, zc, type, listener):
+    def __init__(self, zc, type_, handlers):
         """Creates a browser for a specific type"""
         threading.Thread.__init__(self)
         self.daemon = True
         self.zc = zc
-        self.type = type
-        self.listener = listener
+        self.type = type_
         self.services = {}
         self.next_time = current_time_millis()
         self.delay = _BROWSER_TIME
@@ -946,10 +972,28 @@ def __init__(self, zc, type, listener):
         self.zc.add_listener(self, DNSQuestion(self.type, _TYPE_PTR, _CLASS_IN))
         self.start()
 
+        self._service_state_changed = Signal()
+        for h in handlers:
+            self.service_state_changed.register_handler(h)
+
+    @property
+    def service_state_changed(self):
+        return self._service_state_changed.registration_interface
+
     def update_record(self, zc, now, record):
         """Callback invoked by Zeroconf when new information arrives.
 
         Updates information required by browser in the Zeroconf cache."""
+
+        def enqueue_callback(state_change, name):
+            self._handlers_to_call.append(
+                lambda zeroconf: self._service_state_changed.fire(
+                    zeroconf=zeroconf,
+                    service_type=self.type,
+                    name=name,
+                    state_change=state_change,
+                ))
+
         if record.type == _TYPE_PTR and record.name == self.type:
             expired = record.is_expired(now)
             service_key = record.alias.lower()
@@ -958,15 +1002,13 @@ def update_record(self, zc, now, record):
             except KeyError:
                 if not expired:
                     self.services[service_key] = record
-                    self._handlers_to_call.append(
-                        lambda x: self.listener.add_service(x, self.type, record.alias))
+                    enqueue_callback(ServiceStateChange.Added, record.alias)
             else:
                 if not expired:
                     old_record.reset_ttl(record)
                 else:
                     del self.services[service_key]
-                    self._handlers_to_call.append(
-                        lambda x: self.listener.remove_service(x, self.type, record.alias))
+                    enqueue_callback(ServiceStateChange.Removed, record.alias)
                     return
 
             expires = record.get_expiration_time(75)
@@ -1197,6 +1239,12 @@ class InterfaceChoice(enum.Enum):
     All = 2
 
 
+@enum.unique
+class ServiceStateChange(enum.Enum):
+    Added = 1
+    Removed = 2
+
+
 HOST_ONLY_NETWORK_MASK = '255.255.255.255'