add api urls and signals interface for detail route buttons

netbox/extras/plugins/signals.py

@@ -0,0 +1,34 @@
+import django.dispatch
+from django.dispatch.dispatcher import NO_RECEIVERS
+
+
+class PluginSignal(django.dispatch.Signal):
+
+    def _sorted_receivers(self, sender):
+        orig_list = self._live_receivers(sender)
+        sorted_list = sorted(
+            orig_list,
+            key=lambda receiver: (
+                receiver.__module__,
+                receiver.__name__,
+            )
+        )
+        return sorted_list
+
+    def send(self, sender, **kwargs):
+        responses = []
+        if not self.receivers or self.sender_receivers_cache.get(sender) is NO_RECEIVERS:
+            return responses
+
+        for receiver in self._sorted_receivers(sender):
+            response = receiver(signal=self, sender=sender, **kwargs)
+            responses.append((receiver, response))
+        return responses
+
+
+"""
+This signal collects templates which render buttons for object detail pages
+"""
+register_detail_page_buttons = PluginSignal(
+    providing_args=[]
+)