allow extractors to register a 'finalize()' method

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Changelog
 
+## Unreleased
+
 ## 1.18.4 - 2021-09-04
 ### Additions
 - [420chan] add `thread` and `board` extractors ([#1773](https://github.com/mikf/gallery-dl/issues/1773))

gallery_dl/extractor/common.py

@@ -42,6 +42,7 @@ class Extractor():
     def __init__(self, match):
         self.log = logging.getLogger(self.category)
         self.url = match.string
+        self.finalize = None
 
         if self.basecategory:
             self.config = self._config_shared

gallery_dl/job.py

@@ -109,6 +109,8 @@ class Job():
                 log.info("No results for %s", extractor.url)
         finally:
             self.handle_finalize()
+            if extractor.finalize:
+                extractor.finalize()
 
         return self.status
 

gallery_dl/version.py

@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
-__version__ = "1.18.4"
+__version__ = "1.19.0-dev"