bpo-36144: Add PEP 584 operators to collections.ChainMap (#18832)
* Update ChainMap to include | and |=
Created __ior__, __or__ and __ror__ methods in ChainMap class.
* Update ACKS
* Update docs
* Update test_collections.py to include test_issue584().
Added testing for | and |= operators for ChainMap objects.
* Update test_union_operators
Renamed test_union operators, fixed errors and style problems raised by brandtbucher.
* Update test_union_operators in TestChainMap
Added testing for union operator between ChainMap and iterable of key-value pairs.
* Update test_union operators in test_collections.py
Gave more descriptive variable names and eliminated unnecessary tmp variable.
* Update test_union_operators in test_collections.py
Added cm3
* Check .maps rather than Chainmap equality.
* Add news entry
* Update Lib/test/test_collections.py
Co-Authored-By: Brandt Bucher <brandtbucher@gmail.com>
* Removed whitespace
* Added Guido's changes
* Fixed Docs
* Removed whitespace
Co-authored-by: Brandt Bucher <brandtbucher@gmail.com>
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 92520b0..47c500b 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -232,6 +232,51 @@
for k, v in dict(a=1, B=20, C=30, z=100).items(): # check get
self.assertEqual(d.get(k, 100), v)
+ def test_union_operators(self):
+ cm1 = ChainMap(dict(a=1, b=2), dict(c=3, d=4))
+ cm2 = ChainMap(dict(a=10, e=5), dict(b=20, d=4))
+ cm3 = cm1.copy()
+ d = dict(a=10, c=30)
+ pairs = [('c', 3), ('p',0)]
+
+ tmp = cm1 | cm2 # testing between chainmaps
+ self.assertEqual(tmp.maps, [cm1.maps[0] | dict(cm2), *cm1.maps[1:]])
+ cm1 |= cm2
+ self.assertEqual(tmp, cm1)
+
+ tmp = cm2 | d # testing between chainmap and mapping
+ self.assertEqual(tmp.maps, [cm2.maps[0] | d, *cm2.maps[1:]])
+ self.assertEqual((d | cm2).maps, [d | dict(cm2)])
+ cm2 |= d
+ self.assertEqual(tmp, cm2)
+
+ # testing behavior between chainmap and iterable key-value pairs
+ with self.assertRaises(TypeError):
+ cm3 | pairs
+ cm3 |= pairs
+ self.assertEqual(cm3.maps, [cm3.maps[0] | dict(pairs), *cm3.maps[1:]])
+
+ # testing proper return types for ChainMap and it's subclasses
+ class Subclass(ChainMap):
+ pass
+
+ class SubclassRor(ChainMap):
+ def __ror__(self, other):
+ return super().__ror__(other)
+
+ tmp = ChainMap() | ChainMap()
+ self.assertIs(type(tmp), ChainMap)
+ self.assertIs(type(tmp.maps[0]), dict)
+ tmp = ChainMap() | Subclass()
+ self.assertIs(type(tmp), ChainMap)
+ self.assertIs(type(tmp.maps[0]), dict)
+ tmp = Subclass() | ChainMap()
+ self.assertIs(type(tmp), Subclass)
+ self.assertIs(type(tmp.maps[0]), dict)
+ tmp = ChainMap() | SubclassRor()
+ self.assertIs(type(tmp), SubclassRor)
+ self.assertIs(type(tmp.maps[0]), dict)
+
################################################################################
### Named Tuples