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.travis.yml

@@ -2,7 +2,6 @@ language: python
 python:
     - "2.6"
     - "2.7"
-    - "3.2"
     - "3.3"
     - "3.4"
 

chest/core.py

@@ -95,6 +95,7 @@ def __init__(self, data=None, path=None, available_memory=None,
                  on_miss=_do_nothing, on_overflow=_do_nothing,
                  open=open,
                  open_many=_open_many,
+                 readonly=False,
                  mode='b'):
         # In memory storage
         self.inmem = data or dict()
@@ -115,6 +116,7 @@ def __init__(self, data=None, path=None, available_memory=None,
         self.open = open
         self.open_many = open_many
         self._key_to_filename = key_to_filename
+        self.readonly = readonly
 
         keyfile = os.path.join(self.path, '.keys')
         try:
@@ -134,6 +136,9 @@ def __init__(self, data=None, path=None, available_memory=None,
         self._on_miss = on_miss
         self._on_overflow = on_overflow
 
+        if (not self._explicitly_given_path) and self.readonly:
+            raise TypeError("Can't create an empty readonly chest")
+
     def __str__(self):
         return '<chest at %s>' % self.path
 
@@ -196,6 +201,9 @@ def _update_lru(self, key):
         self.heap[key] = self.counter
 
     def __delitem__(self, key):
+        if self.readonly:
+            raise TypeError("Can't delete from readonly chest")
+
         if key in self.inmem:
             self.memory_usage -= nbytes(self.inmem[key])
             del self.inmem[key]
@@ -209,6 +217,9 @@ def __delitem__(self, key):
         del self._keys[key]
 
     def __setitem__(self, key, value):
+        if self.readonly:
+            raise TypeError("Can't assign in readonly chest")
+
         with self.lock:
             if key in self._keys:
                 del self[key]
@@ -223,7 +234,7 @@ def __setitem__(self, key, value):
 
     def __del__(self):
         if self._explicitly_given_path:
-            if os.path.exists(self.path):
+            if os.path.exists(self.path) and not self.readonly:
                 self.flush()
             else:
                 with self.lock:

chest/tests/test_core.py

@@ -458,3 +458,38 @@ def test_prefetch():
         assert not raises(KeyError, lambda: c[1])
         c.prefetch([1, 2])
         assert not raises(KeyError, lambda: c[2])
+
+
+def test_readonly():
+    with tmp_chest(path="here") as c1:
+        c1[0] = 0
+        c1["foo"] = "bar"
+        c1.flush()
+        with tmp_chest(path="here", readonly=True) as c2:
+            assert c2[0] == 0
+            assert c2["foo"] == "bar"
+            try:
+                c2[0] = 1
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+            try:
+                c2["spam"] = "eggs"
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+            try:
+                del c2["foo"]
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+
+
+def test_readonly_nopath():
+    assert raises(TypeError, lambda: Chest(readonly=True))