fix is_4cat_class (#398)

* fix is_4cat_class

* add back helpful explanation comment

backend/lib/processor.py

@@ -863,4 +863,16 @@ def process(self):
 		"""
 		pass
 
+	@staticmethod
+	def is_4cat_processor():
+		"""
+		Is this a 4CAT processor?
+
+		This is used to determine whether a class is a 4CAT
+		processor.
+		
+		:return:  True
+		"""
+		return True
+
 

backend/lib/worker.py

@@ -167,3 +167,27 @@ def work(self):
 		classes should implement this method.
 		"""
 		pass
+
+	@staticmethod
+	def is_4cat_class():
+		"""
+		Is this a 4CAT class?
+
+		This is used to determine whether a class is a 4CAT worker or a
+		processor. This method should always return True for workers.
+
+		:return:  True
+		"""
+		return True
+
+	@staticmethod
+	def is_4cat_processor():
+		"""
+		Is this a 4CAT processor?
+
+		This is used to determine whether a class is a 4CAT
+		processor.
+		
+		:return:  False
+		"""
+		return False

common/lib/module_loader.py

@@ -72,20 +72,21 @@ def is_4cat_class(object, only_processors=False):
         # it would be super cool to just use issubclass() here!
         # but that requires importing the classes themselves, which leads to
         # circular imports
-        # todo: fix this because this sucks
-        # agreed - Dale
-        parent_classes = {"BasicWorker", "BasicProcessor", "Search", "SearchWithScope", "Search4Chan",
-                          "ProcessorPreset", "TwitterStatsBase", "BaseFilter", "TwitterAggregatedStats", "ColumnFilter",
-                          "BasicJSONScraper", "BoardScraper4chan", "ThreadScraper4chan"}
-        if only_processors:
-            # only allow processors
-            for worker_only_class in ["BasicWorker", "BasicJSONScraper", "BoardScraper4chan", "ThreadScraper4chan"]:
-                parent_classes.remove(worker_only_class)
-
-        return inspect.isclass(object) and \
-               parent_classes & set([f.__name__ for f in object.__bases__]) and \
-               object.__name__ not in("BasicProcessor", "BasicWorker") and \
-               not inspect.isabstract(object)
+        if inspect.isclass(object):
+            if object.__name__ in("BasicProcessor", "BasicWorker") or inspect.isabstract(object):
+                # ignore abstract and base classes
+                return False
+
+            if hasattr(object, "is_4cat_class"):
+                if only_processors:
+                    if hasattr(object, "is_4cat_processor"):
+                        return object.is_4cat_processor()
+                    else:
+                        return False
+                else:
+                    return object.is_4cat_class()
+
+        return False
 
     def load_modules(self):
         """