ch11-24: clean up by @eumiro & sync with Atlas

23-dyn-attr-prop/oscon/explore2.py

@@ -0,0 +1,54 @@
+"""
+explore2.py: Script to explore the OSCON schedule feed
+
+    >>> import json
+    >>> raw_feed = json.load(open('data/osconfeed.json'))
+    >>> feed = FrozenJSON(raw_feed)
+    >>> len(feed.Schedule.speakers)
+    357
+    >>> sorted(feed.Schedule.keys())
+    ['conferences', 'events', 'speakers', 'venues']
+    >>> feed.Schedule.speakers[-1].name
+    'Carina C. Zona'
+    >>> talk = feed.Schedule.events[40]
+    >>> talk.name
+    'There *Will* Be Bugs'
+    >>> talk.speakers
+    [3471, 5199]
+    >>> talk.flavor
+    Traceback (most recent call last):
+      ...
+    KeyError: 'flavor'
+
+"""
+
+# tag::EXPLORE2[]
+from collections import abc
+import keyword
+
+class FrozenJSON:
+    """A read-only façade for navigating a JSON-like object
+       using attribute notation
+    """
+
+    def __new__(cls, arg):  # <1>
+        if isinstance(arg, abc.Mapping):
+            return super().__new__(cls)  # <2>
+        elif isinstance(arg, abc.MutableSequence):  # <3>
+            return [cls(item) for item in arg]
+        else:
+            return arg
+
+    def __init__(self, mapping):
+        self.__data = {}
+        for key, value in mapping.items():
+            if keyword.iskeyword(key):
+                key += '_'
+            self.__data[key] = value
+
+    def __getattr__(self, name):
+        if hasattr(self.__data, name):
+            return getattr(self.__data, name)
+        else:
+            return FrozenJSON(self.__data[name])  # <4>
+# end::EXPLORE2[]