Add deep_update from pydantic

src/epydeck/__init__.py

@@ -142,3 +142,19 @@ def dumps(deck: dict) -> str:
     fh = StringIO()
     dump(deck, fh)
     return fh.getvalue()
+
+
+def deep_update(deck: dict, *deck_patches: dict) -> dict:
+    """Update `deck` recursively (like `dict.update` without
+    clobbering the nested dicts)
+
+    Lightly adapted from pydantic, MIT licence
+    """
+    updated_deck = deck.copy()
+    for deck_patch in deck_patches:
+        for k, v in deck_patch.items():
+            if k in updated_deck and isinstance(updated_deck[k], dict) and isinstance(v, dict):
+                updated_deck[k] = deep_update(updated_deck[k], v)
+            else:
+                updated_deck[k] = v
+    return updated_deck

test/test_epydeck.py

@@ -0,0 +1,41 @@
+import epydeck
+
+
+def test_deep_update():
+    deck = {
+        "repeated_block": {
+            "first": {"name": "first", "a": 1, "b": 2, "c": 3},
+            "second": {"name": "second", "a": 4, "b": 5, "c": 6},
+        },
+        "block": {
+            "a": 1,
+            "b": 2.3,
+            "c": "electron",
+            "d": "10 * femto",
+            "e": False,
+            "f": True,
+        },
+    }
+
+    patch = {
+        "repeated_block": {"first": {"b": 7}},
+        "block": {"b": 7.8, "e": True, "d": "20 * femto"}}
+
+    expected = {
+        "repeated_block": {
+            "first": {"name": "first", "a": 1, "b": 7, "c": 3},
+            "second": {"name": "second", "a": 4, "b": 5, "c": 6},
+        },
+        "block": {
+            "a": 1,
+            "b": 7.8,
+            "c": "electron",
+            "d": "20 * femto",
+            "e": True,
+            "f": True,
+        },
+    }
+
+    result = epydeck.deep_update(deck, patch)
+
+    assert result == expected