added package structure

bstrd/ltddict.py

@@ -0,0 +1,22 @@
+from collections import OrderedDict
+
+
+class LimitedDict(OrderedDict):
+
+    def __init__(self, *args, maxlen=None, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.maxlen = maxlen
+        self._ensure_length()
+
+    def __setitem__(self, *args):
+        super().__setitem__(*args)
+        self._ensure_length()
+
+    def _ensure_length(self):
+        if self.maxlen is None:
+            return
+        while len(self) > self.maxlen:
+            self.popitem(last=False)
+
+
+