[util] extend CustomNone with an __index__ method (#6009)

- Make it compatible with functions expecting integer arguments
- Simplify and reuse some method definitions

gallery_dl/util.py

@@ -520,14 +520,9 @@ class CustomNone():
     """None-style type that supports more operations than regular None"""
     __slots__ = ()
 
-    def __getattribute__(self, _):
-        return self
-
-    def __getitem__(self, _):
-        return self
-
-    def __iter__(self):
-        return self
+    __getattribute__ = identity
+    __getitem__ = identity
+    __iter__ = identity
 
     def __call__(self, *args, **kwargs):
         return self
@@ -536,10 +531,6 @@ class CustomNone():
     def __next__():
         raise StopIteration
 
-    @staticmethod
-    def __bool__():
-        return False
-
     def __eq__(self, other):
         return self is other
 
@@ -550,6 +541,7 @@ class CustomNone():
     __le__ = true
     __gt__ = false
     __ge__ = false
+    __bool__ = false
 
     __add__ = identity
     __sub__ = identity
@@ -588,9 +580,8 @@ class CustomNone():
     def __len__():
         return 0
 
-    @staticmethod
-    def __hash__():
-        return 0
+    __hash__ = __len__
+    __index__ = __len__
 
     @staticmethod
     def __format__(_):

test/test_util.py

@@ -12,6 +12,7 @@ import sys
 import unittest
 
 import io
+import time
 import random
 import string
 import datetime
@@ -741,6 +742,9 @@ def hash(value):
 
         self.assertFalse(obj)
         self.assertEqual(len(obj), 0)
+        self.assertEqual(int(obj), 0)
+        self.assertEqual(hash(obj), 0)
+
         self.assertEqual(str(obj), str(None))
         self.assertEqual(repr(obj), repr(None))
         self.assertEqual(format(obj), str(None))
@@ -751,6 +755,7 @@ def hash(value):
         self.assertIs(obj(), obj)
         self.assertIs(obj(1, "a"), obj)
         self.assertIs(obj(foo="bar"), obj)
+        self.assertIs(iter(obj), obj)
         self.assertEqual(util.json_dumps(obj), "null")
 
         self.assertLess(obj, "foo")
@@ -797,6 +802,12 @@ def hash(value):
         mapping = {}
         mapping[obj] = 123
         self.assertIn(obj, mapping)
+        self.assertEqual(mapping[obj], 123)
+
+        array = [1, 2, 3]
+        self.assertEqual(array[obj], 1)
+
+        self.assertTrue(time.localtime(obj))
 
         i = 0
         for _ in obj: