sync to Atlas repo

dicts/strkeydict0_userdictsub.py

@@ -0,0 +1,53 @@
+"""StrKeyDict0 converts non-string keys to `str` on lookup
+
+# BEGIN STRKEYDICT0_TESTS
+
+Tests for item retrieval using `d[key]` notation::
+
+    >>> d = StrKeyDict0([('2', 'two'), ('4', 'four')])
+    >>> d['2']
+    'two'
+    >>> d[4]
+    'four'
+    >>> d[1]
+    Traceback (most recent call last):
+      ...
+    KeyError: '1'
+
+
+Tests for item retrieval using `d.get(key)` notation::
+
+    >>> d.get('2')
+    'two'
+    >>> d.get(4)
+    'four'
+    >>> d.get(1, 'N/A')
+    'N/A'
+
+
+Tests for the `in` operator::
+
+    >>> 2 in d
+    True
+    >>> 1 in d
+    False
+
+# END STRKEYDICT0_TESTS
+"""
+
+# BEGIN STRKEYDICT0
+
+import collections
+
+
+class StrKeyDict0(collections.UserDict):  # <1>
+
+    def __missing__(self, key):
+        if isinstance(key, str):  # <2>
+            raise KeyError(key)
+        return self[str(key)]  # <3>
+
+    def __contains__(self, key):
+        return str(key) in self.data  # <3>
+
+# END STRKEYDICT0