add 'python' post processor

similar to 'exec' but calls a Python function

docs/configuration.rst

@@ -4748,6 +4748,50 @@ Description
     |datetime|_ object.
 
 
+python.archive
+--------------
+Type
+    |Path|_
+Description
+    File to store IDs of called Python functions in,
+    similar to `extractor.*.archive`_.
+
+    ``archive-format``, ``archive-prefix``, and ``archive-pragma`` options,
+    akin to
+    `extractor.*.archive-format`_,
+    `extractor.*.archive-prefix`_, and
+    `extractor.*.archive-pragma`_, are supported as well.
+
+
+python.event
+------------
+Type
+    ``string``
+Default
+    ``"file"``
+Description
+    The event for which `python.function`_ gets called.
+
+    See `metadata.event`_ for a list of available events.
+
+
+python.function
+---------------
+Type
+    ``string``
+Example
+    * ``"my_module:generate_text"``
+    * ``"~/.local/share/gdl-utils.py:resize"``
+Description
+    The Python function to call.
+
+    This function gets specified as ``<module>:<function name>``
+    and gets called with the current metadata dict as argument.
+
+    ``module`` is either an importable Python module name
+    or the |Path|_ to a `.py` file,
+
+
 ugoira.extension
 ----------------
 Type
@@ -5345,6 +5389,8 @@ Description
         Write metadata to separate files
     ``mtime``
         Set file modification time according to its metadata
+    ``python``
+        Call Python functions
     ``ugoira``
         Convert Pixiv Ugoira to WebM using `FFmpeg <https://www.ffmpeg.org/>`__
     ``zip``

gallery_dl/postprocessor/__init__.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2018-2021 Mike Fährmann
+# Copyright 2018-2023 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
@@ -14,6 +14,7 @@ modules = [
     "exec",
     "metadata",
     "mtime",
+    "python",
     "ugoira",
     "zip",
 ]

gallery_dl/postprocessor/python.py

@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2023 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
+# published by the Free Software Foundation.
+
+"""Run Python functions"""
+
+from .common import PostProcessor
+from .. import util
+
+
+class PythonPP(PostProcessor):
+
+    def __init__(self, job, options):
+        PostProcessor.__init__(self, job)
+
+        spec = options["function"]
+        module_name, _, function_name = spec.rpartition(":")
+        module = util.import_file(module_name)
+        self.function = getattr(module, function_name)
+
+        self._init_archive(job, options)
+        if self.archive:
+            self.run = self.run_archive
+
+        events = options.get("event")
+        if events is None:
+            events = ("file",)
+        elif isinstance(events, str):
+            events = events.split(",")
+        job.register_hooks({event: self.run for event in events}, options)
+
+    def run(self, pathfmt):
+        self.function(pathfmt.kwdict)
+
+    def run_archive(self, pathfmt):
+        kwdict = pathfmt.kwdict
+        if self.archive.check(kwdict):
+            return
+        self.function(kwdict)
+        self.archive.add(kwdict)
+
+
+__postprocessor__ = PythonPP