abstract serializer, update to use serializer interface in dbm adpater

rltk/io/adapter/dbm_adapter.py

@@ -2,26 +2,28 @@
 import pickle
 
 from rltk.io.adapter import Adapter
+from rltk.io.serializer import Serializer, PickleSerializer
 from rltk.record import Record
 
 
 class DBMAdapter(Adapter):
-    def __init__(self, filename, dbm_class=dbm.ndbm):
+    def __init__(self, filename, dbm_class=dbm.ndbm, serializer:Serializer=PickleSerializer()):
         """
         :dbm_class dbm, dbm.gnu, dbm.ndbm, dbm.dumb (same as dbm)
         """
         self._db = dbm_class.open(filename, 'c')
+        self._serializer = serializer
 
         # not all dbm supports iterator, simulate an iterator by getting a key set
         # key will be in byte form once read out from dbm, needs to be converted to string
         self._ids = set([k.decode('utf-8') for k in self._db.keys()])
 
     def get(self, record_id):
-        return pickle.loads(self._db.get(record_id))
+        return self._serializer.loads(self._db.get(record_id))
 
     def set(self, record_id, record: Record):
         self._ids.add(record_id)
-        self._db[record_id] = pickle.dumps(record)
+        self._db[record_id] = self._serializer.dumps(record)
 
     def __next__(self):
         for i in self._ids:

rltk/io/serializer/__init__.py

@@ -0,0 +1,2 @@
+from rltk.io.serializer.serializer import Serializer
+from rltk.io.serializer.pickle_serializer import PickleSerializer

rltk/io/serializer/pickle_serializer.py

@@ -0,0 +1,12 @@
+import pickle
+
+from rltk.io.serializer import Serializer
+
+
+class PickleSerializer(Serializer):
+
+    def loads(self, string):
+        return pickle.loads(string)
+
+    def dumps(self, obj):
+        return pickle.dumps(obj)

rltk/io/serializer/serializer.py

@@ -0,0 +1,6 @@
+class Serializer(object):
+    def loads(self, obj):
+        raise NotImplementedError
+
+    def dumps(self, obj):
+        raise NotImplementedError