Introducing deepmerge. It’s a library designed to provide simple
controls around a merging system for basic Python data structures like dicts and lists.
It provides a few common cases for merging (like always merge + override, or raise an exception):
from deepmerge import always_merger, merge_or_raise
base = {
"a": ["b"],
"c": 1,
"nested": {
"nested_dict": "value",
"nested_list": ["a"]
}
}
nxt = {
"new_key": "new_value",
"nested": {
"nested_dict": "new_value",
"nested_list": ["b"],
"new_nested_key": "value"
}
}
always_merge(base, nxt)
assert base == {
"a": ["b"],
"c": 1,
"new_key": "new_value"
"nested": {
"nested_dict": "new_value",
"nested_list": ["a", "b"],
"new_nested_key": "value"
}
}
deepmerge allows customization as well, for when you want to specify
the merging strategy:
from deepmerge import Merger
my_merger = Merger(
# pass in a list of tuples,with the
# strategies you are looking to apply
# to each type.
[
(list, ["prepend"]),
(dict, ["merge"])
],
# next, choose the fallback strategies,
# applied to all other types:
["override"],
# finally, choose the strategies in
# the case where the types conflict:
["override"]
)
base = {"foo": ["bar"]}
next = {"bar": "baz"}
my_merger.merge(base, next)
assert base == {"foo": ["bar"], "bar": "baz"}
For each strategy choice, pass in a list of strings specifying built in strategies,
or a function defining your own:
def merge_sets(merger, path, base, nxt):
base |= nxt
return base
def merge_list(merger, path, base, nxt):
if len(nxt) > 0:
base.append(nxt[-1])
return base
return Merger(
[
(list, merge_list),
(dict, "merge"),
(set, merge_sets)
],
[],
[],
)
That’s it! Give and try, and Pull Requests are always encouraged.
