update from Atlas with major reorg

attic/interfaces/dict_subclass.py

@@ -0,0 +1,45 @@
+# Code and text by BitBucket user "enigmacurry" posted to
+# https://bitbucket.org/pypy/pypy/issue/708/discrepancy-in-dict-subclass-__getitem__
+# Adapted by Luciano Ramalho:
+# - changed comments to docstring to run with doctest;
+# - added test for Test class raising exception
+# - and added () to print.
+
+"""
+This is a test case to describe a bug I'm seeing in PyPy 1.5. I have
+a Cache object that is a dictionary that supports lookup via regular
+attribute access. For instance:
+
+    >>> c = Cache()
+    >>> c["asdf"] = "asdf"
+    >>> c.asdf == c["asdf"]
+    True
+    >>> t = Test()
+    >>> t["asdf"] = "asdf"
+    >>> t.asdf == t["asdf"]
+    Traceback (most recent call last):
+      ...
+    Exception: Trying to getitem: asdf
+
+When looking up keys via attribute, PyPy 1.5 calls __getitem__
+whereas CPython 2.7.1 does not.
+"""
+
+class Cache(dict):
+    "A dictionary that supports attribute style key lookup"
+    def __init__(self, **kw):
+        dict.__init__(self, kw)
+        self.__dict__ = self
+
+class Test(Cache):
+    def __getitem__(self, item):
+        # I want to process items differently than attributes:
+        raise Exception("Trying to getitem: %s" % item)
+
+if __name__ == "__main__":
+    t = Test()
+    t["asdf"] = "asdf"
+    #CPython does not call __getitem__ .. PyPy does:
+    print(t.asdf)
+    #Doesn't matter if it's a member of __dict__ or not:
+    print(t.__getattribute__)