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

docs/configuration.rst

@@ -8017,6 +8017,23 @@ Description
     See `metadata.event`_ for a list of available events.
 
 
+python.expression
+-----------------
+Type
+    ``string``
+Example
+    * ``"print('Foo Bar')"``
+    * ``"terminate()"``
+Description
+    A
+    `Python expression <https://docs.python.org/3/glossary.html#term-expression>`__
+    to
+    `evaluate <https://docs.python.org/3/library/functions.html#eval>`__.
+
+    Note: Only used with
+    `"mode": "eval" <python.mode_>`__
+
+
 python.function
 ---------------
 Type
@@ -8034,6 +8051,23 @@ Description
     It gets called with the current metadata dict as argument.
 
 
+python.mode
+-----------
+Type
+    ``string``
+Default
+    ``"function"``
+Description
+    Selects what Python code to run.
+
+    ``"eval"``
+        Evaluate an
+        `expression <python.expression_>`__
+    ``function"``
+        Call a
+        `function <python.function_>`__
+
+
 rename.from
 -----------
 Type

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:

test/test_postprocessor.py

@@ -20,7 +20,7 @@ import collections
 from datetime import datetime
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
-from gallery_dl import extractor, output, path, util  # noqa E402
+from gallery_dl import extractor, output, path, util, exception  # noqa E402
 from gallery_dl import postprocessor, config  # noqa E402
 from gallery_dl.postprocessor.common import PostProcessor  # noqa E402
 
@@ -867,6 +867,18 @@ class PythonTest(BasePostprocessorTest):
         self._trigger()
         self.assertEqual(self.pathfmt.kwdict["_result"], 24)
 
+    def test_eval(self):
+        self._create({"mode": "eval", "expression": "abort()"})
+
+        with self.assertRaises(exception.StopExtraction):
+            self._trigger()
+
+    def test_eval_auto(self):
+        self._create({"expression": "abort()"})
+
+        with self.assertRaises(exception.StopExtraction):
+            self._trigger()
+
     def _write_module(self, path):
         with open(path, "w") as fp:
             fp.write("""