[pp:python] add '"mode": "eval"'

gallery_dl/postprocessor/python.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-# Copyright 2023 Mike Fährmann
+# Copyright 2023-2025 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
@@ -17,10 +17,14 @@ 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)
+        mode = options.get("mode")
+        if mode == "eval" or not mode and options.get("expression"):
+            self.function = util.compile_expression(options["expression"])
+        else:
+            spec = options["function"]
+            module_name, _, function_name = spec.rpartition(":")
+            module = util.import_file(module_name)
+            self.function = getattr(module, function_name)
 
         events = options.get("event")
         if events is None: