implement 'globals' option

docs/configuration.rst

@@ -4694,6 +4694,29 @@ Description
     or by `extractor.modules`_.
 
 
+globals
+-------
+Type
+    * |Path|_
+    * ``string``
+Example
+    * ``"~/.local/share/gdl-globals.py"``
+    * ``"gdl-globals"``
+Default
+    The ``GLOBALS`` dict in
+    `util.py <../gallery_dl/util.py>`__
+Description
+    Path to or name of an
+    `importable <https://docs.python.org/3/reference/import.html>`__
+    Python module whose namespace gets used as an alternative
+    |globals parameter|__
+    for compiled Python expressions.
+
+.. |globals parameter| replace:: ``globals`` parameter
+.. __: https://docs.python.org/3/library/functions.html#eval
+
+
+
 cache.file
 ----------
 Type

gallery_dl/__init__.py

@@ -110,6 +110,11 @@ def main():
             from . import formatter
             formatter._SEPARATOR = separator
 
+        # eval globals
+        path = config.get((), "globals")
+        if path:
+            util.GLOBALS = util.import_file(path).__dict__
+
         # loglevels
         output.configure_logging(args.loglevel)
         if args.loglevel >= logging.ERROR:

gallery_dl/util.py

@@ -619,9 +619,28 @@ GLOBALS = {
 }
 
 
-def compile_expression(expr, name="<expr>", globals=GLOBALS):
+def compile_expression(expr, name="<expr>", globals=None):
     code_object = compile(expr, name, "eval")
-    return functools.partial(eval, code_object, globals)
+    return functools.partial(eval, code_object, globals or GLOBALS)
+
+
+def import_file(path):
+    """Import a Python module from a filesystem path"""
+    path, name = os.path.split(path)
+
+    name, sep, ext = name.rpartition(".")
+    if not sep:
+        name = ext
+
+    if path:
+        path = expand_path(path)
+        sys.path.insert(0, path)
+        try:
+            return __import__(name)
+        finally:
+            del sys.path[0]
+    else:
+        return __import__(name)
 
 
 def build_duration_func(duration, min=0.0):

test/test_util.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-# Copyright 2015-2022 Mike Fährmann
+# Copyright 2015-2023 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
@@ -15,6 +15,7 @@ import io
 import random
 import string
 import datetime
+import tempfile
 import itertools
 import http.cookiejar
 
@@ -458,6 +459,56 @@ class TestOther(unittest.TestCase):
         with self.assertRaises(exception.StopExtraction):
             expr()
 
+    def test_import_file(self):
+        module = util.import_file("datetime")
+        self.assertIs(module, datetime)
+
+        with tempfile.TemporaryDirectory() as path:
+            file = path + "/module_test.py"
+            with open(file, "w") as fp:
+                fp.write("""
+import datetime
+key = "foobar"
+value = 123
+""")
+            module = util.import_file(file)
+
+        self.assertEqual(module.__name__, "module_test")
+        self.assertEqual(module.key, "foobar")
+        self.assertEqual(module.value, 123)
+        self.assertIs(module.datetime, datetime)
+
+    def test_custom_globals(self):
+        value = {"v": "foobar"}
+        result = "8843d7f92416211de9ebb963ff4ce28125932878"
+
+        expr = util.compile_expression("hash_sha1(v)")
+        self.assertEqual(expr(value), result)
+
+        expr = util.compile_expression("hs(v)", globals={"hs": util.sha1})
+        self.assertEqual(expr(value), result)
+
+        with tempfile.TemporaryDirectory() as path:
+            file = path + "/module_sha1.py"
+            with open(file, "w") as fp:
+                fp.write("""
+import hashlib
+def hash(value):
+    return hashlib.sha1(value.encode()).hexdigest()
+""")
+            module = util.import_file(file)
+
+        expr = util.compile_expression("hash(v)", globals=module.__dict__)
+        self.assertEqual(expr(value), result)
+
+        GLOBALS_ORIG = util.GLOBALS
+        try:
+            util.GLOBALS = module.__dict__
+            expr = util.compile_expression("hash(v)")
+        finally:
+            util.GLOBALS = GLOBALS_ORIG
+        self.assertEqual(expr(value), result)
+
     def test_build_duration_func(self, f=util.build_duration_func):
 
         def test_single(df, v):