🔀 Merge thodnev/ptb into ptb/promises-with-exceptions

#529

telegram/ext/conversationhandler.py

@@ -128,10 +128,16 @@ class ConversationHandler(Handler):
             self.logger.debug('waiting for promise...')
 
             old_state, new_state = state
-            new_state.result(timeout=self.run_async_timeout)
+            error = False
+            try:
+                res = new_state.result(timeout=self.run_async_timeout)
+            except Exception as exc:
+                self.logger.exception("promise function raised exception: %s" %
+                                      exc)
+                error = True
 
-            if new_state.done.is_set():
-                self.update_state(new_state.result(), key)
+            if not error and new_state.done.is_set():
+                self.update_state(res, key)
                 state = self.conversations.get(key)
 
             else:

telegram/ext/dispatcher.py

@@ -159,11 +159,7 @@ class Dispatcher(object):
                                   len(self.__async_threads))
                 break
 
-            try:
-                promise.run()
-
-            except:
-                self.logger.exception("run_async function raised exception")
+            promise.run()
 
     def run_async(self, func, *args, **kwargs):
         """Queue a function (with given args/kwargs) to be run asynchronously.

telegram/utils/promise.py

@@ -30,17 +30,23 @@ class Promise(object):
         self.kwargs = kwargs
         self.done = Event()
         self._result = None
+        self._exception = None
 
     def run(self):
         try:
             self._result = self.pooled_function(*self.args, **self.kwargs)
 
-        except:
-            raise
+        except Exception as exc:
+            self._exception = exc
 
         finally:
             self.done.set()
 
+    def __call__(self):
+        self.run()
+
     def result(self, timeout=None):
         self.done.wait(timeout=timeout)
+        if self._exception is not None:
+            raise self._exception
         return self._result