diff options
| -rw-r--r-- | Doc/library/collections.rst | 3 | ||||
| -rw-r--r-- | Lib/collections/__init__.py | 19 | ||||
| -rw-r--r-- | Lib/test/test_collections.py | 45 | ||||
| -rw-r--r-- | Misc/ACKS | 1 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2020-03-07-11-26-08.bpo-36144.FG9jqy.rst | 1 |
5 files changed, 69 insertions, 0 deletions
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst index 72d1052..c9533a3 100644 --- a/Doc/library/collections.rst +++ b/Doc/library/collections.rst @@ -116,6 +116,9 @@ The class can be used to simulate nested scopes and is useful in templating. >>> list(combined) ['music', 'art', 'opera'] + .. versionchanged:: 3.9 + Added support for ``|`` and ``|=`` operators, specified in :pep:`584`. + .. seealso:: * The `MultiContext class diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py index 18255da..e198406 100644 --- a/Lib/collections/__init__.py +++ b/Lib/collections/__init__.py @@ -979,6 +979,25 @@ class ChainMap(_collections_abc.MutableMapping): 'Clear maps[0], leaving maps[1:] intact.' self.maps[0].clear() + def __ior__(self, other): + self.maps[0] |= other + return self + + def __or__(self, other): + if isinstance(other, _collections_abc.Mapping): + m = self.maps[0].copy() + m.update(other) + return self.__class__(m, *self.maps[1:]) + return NotImplemented + + def __ror__(self, other): + if isinstance(other, _collections_abc.Mapping): + m = dict(other) + for child in reversed(self.maps): + m.update(child) + return self.__class__(m) + return NotImplemented + ################################################################################ ### UserDict 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 @@ class TestChainMap(unittest.TestCase): 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 @@ -233,6 +233,7 @@ Floris Bruynooghe Matt Bryant Stan Bubrouski Brandt Bucher +Curtis Bucher Colm Buckley Erik de Bueger Jan-Hein Bührman diff --git a/Misc/NEWS.d/next/Library/2020-03-07-11-26-08.bpo-36144.FG9jqy.rst b/Misc/NEWS.d/next/Library/2020-03-07-11-26-08.bpo-36144.FG9jqy.rst new file mode 100644 index 0000000..9deb489 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-03-07-11-26-08.bpo-36144.FG9jqy.rst @@ -0,0 +1 @@ +Added :pep:`584` operators (``|`` and ``|=``) to :class:`collections.ChainMap`. |