Catch dict-like vals in __setitem__, apply from_dict()

nbformat/notebooknode.py

@@ -1,23 +1,50 @@
 """NotebookNode - adding attribute access to dicts"""
 
 from ipython_genutils.ipstruct import Struct
+from collections import Mapping
+
 
 class NotebookNode(Struct):
     """A dict-like node with attribute-access"""
-    pass
+
+    def __setitem__(self, key, value):
+        if isinstance(value, Mapping):
+            value = from_dict(value)
+        super(NotebookNode, self).__setitem__(key, value)
+
+    def update(self, *args, **kwargs):
+        """
+        A dict-like update method based on CPython's MutableMapping `update`
+        method.
+        """
+        if len(args) > 1:
+            raise TypeError('update expected at most 1 arguments, got %d' %
+                            len(args))
+        if args:
+            other = args[0]
+            if isinstance(other, Mapping):
+                for key in other:
+                    self[key] = other[key]
+            elif hasattr(other, "keys"):
+                for key in other.keys():
+                    self[key] = other[key]
+            else:
+                for key, value in other:
+                    self[key] = value
+        for key, value in kwargs.items():
+            self[key] = value
+
 
 def from_dict(d):
     """Convert dict to dict-like NotebookNode
-    
+
     Recursively converts any dict in the container to a NotebookNode.
     This does not check that the contents of the dictionary make a valid
     notebook or part of a notebook.
     """
     if isinstance(d, dict):
-        return NotebookNode({k:from_dict(v) for k,v in d.items()})
+        return NotebookNode({k: from_dict(v) for k, v in d.items()})
     elif isinstance(d, (tuple, list)):
         return [from_dict(i) for i in d]
     else:
         return d
-
-