added map_through

CHANGELOG.md

 # v2.18.4
+
+* added `map_through` to `unpack_dict`

satella/__init__.py

-__version__ = '2.18.4a1'
+__version__ = '2.18.4a2'

satella/coding/transforms/__init__.py

@@ -21,7 +21,8 @@ __all__ = ['stringify', 'split_shuffle_and_join', 'one_tuple', 'none_if_false',
 from satella.coding.typing import T, NoArgCallable, Appendable, Number, Predicate, K, V
 
 
-def unpack_dict(dct: tp.Dict[K, V], *args: K) -> tp.Iterator[V]:
+def unpack_dict(dct: tp.Dict[K, V], *args: K,
+                map_through: tp.Callable[[V], V] = lambda y: y) -> tp.Iterator[V]:
     """
     Unpack a dictionary by accessing it's given keys in parallel.
 
@@ -32,11 +33,13 @@ def unpack_dict(dct: tp.Dict[K, V], *args: K) -> tp.Iterator[V]:
 
     :param dct: dictionary to unpack
     :param args: keys in this dictionary
+    :param map_through: a keyword argument, callable that will be called with
+        each value returned and the result of this callable will be returned
     :return: an iterator
     :raises KeyError: a key was not found
     """
     for key in args:
-        yield dct[key]
+        yield map_through(dct[key])
 
 
 def none_if_false(y: tp.Any) -> tp.Optional[tp.Any]:

tests/test_coding/test_transforms.py

@@ -3,6 +3,7 @@ import operator
 import unittest
 import base64
 
+from satella.coding.predicates import x
 from satella.coding.transforms import stringify, split_shuffle_and_join, one_tuple, \
     merge_series, pad_to_multiple_of_length, clip, b64encode, linear_interpolate, \
     hashables_to_int, none_if_false, merge_list, is_subset, unpack_dict
@@ -14,6 +15,10 @@ class TestTransforms(unittest.TestCase):
         a, b, c = unpack_dict({1: 2, 2: 3, 4: 5}, 1, 2, 4)
         self.assertTrue(a == 2 and b == 3 and c == 5)
 
+        a, b, c = unpack_dict({1: 2, 2: 3, 4: 5}, 1, 2, 4,
+                              map_through=x*2)
+        self.assertTrue(a == 4 and b == 6 and c == 10)
+
     def test_is_subset(self):
         self.assertTrue(is_subset({}, {}))
         self.assertTrue(is_subset({}, {1: 2}))