improve output of active post processor modules

gallery_dl/job.py

@@ -336,7 +336,8 @@ class DownloadJob(Job):
 
         postprocessors = self.extractor.config("postprocessors")
         if postprocessors:
-            self.postprocessors = []
+            pp_list = []
+
             for pp_dict in postprocessors:
                 whitelist = pp_dict.get("whitelist")
                 blacklist = pp_dict.get("blacklist")
@@ -355,9 +356,12 @@ class DownloadJob(Job):
                         "'%s' initialization failed:  %s: %s",
                         name, exc.__class__.__name__, exc)
                 else:
-                    self.postprocessors.append(pp_obj)
-            self.extractor.log.debug(
-                "Active postprocessor modules: %s", self.postprocessors)
+                    pp_list.append(pp_obj)
+
+            if pp_list:
+                self.postprocessors = pp_list
+                self.extractor.log.debug(
+                    "Active postprocessor modules: %s", pp_list)
 
 
 class SimulationJob(DownloadJob):

gallery_dl/postprocessor/common.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2018 Mike Fährmann
+# Copyright 2018-2019 Mike Fährmann
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
@@ -23,3 +23,6 @@ class PostProcessor():
 
     def finalize(self):
         """Cleanup"""
+
+    def __repr__(self):
+        return self.__class__.__name__