chain map
β’ 88 words β’ 1 min
python
from collections import ChainMap
a = {1: 2}
b = {1: 3}
c = {2: 4}
# a has more priority than b, which has more priority than c
d = ChainMap(a, b, c)
assert len(d) == 2
assert d[1] == 2
assert d[2] == 4
d[1] = 3
assert d[1] == 3
assert a[1] == 3
d[2] = 10
assert d[2] == 10
assert a[2] == 10
assert c[2] == 4
del d[2]
assert 2 not in a
e = d.new_child({1: 10})
assert e[1] == 10