Merge pull request #974 from rizar/fix_application_serialization

Fix Application pickling

blocks/bricks/base.py

@@ -326,6 +326,13 @@ def copy_and_tag(variable, role, name):
             return OrderedDict(zip(bound_application.outputs, outputs))
         return unpack(outputs)
 
+    # Application instances are used instead of usual methods in bricks.
+    # The usual methods are not pickled per-se, similarly to classes
+    # and modules. Instead, a reference to the method is put into the pickle.
+    # Here, we ensure the same behaviour for Application instances.
+    def __reduce__(self):
+        return (getattr, (self.brick, self.application_name))
+
 
 class BoundApplication(object):
     """An application method bound to a :class:`Brick` instance."""

tests/bricks/test_bricks.py

@@ -3,6 +3,7 @@
 import theano
 from numpy.testing import assert_allclose, assert_raises
 from theano import tensor
+from six.moves import cPickle
 
 from blocks.bricks import (Identity, Linear, Maxout, LinearMaxout, MLP, Tanh,
                            Sequence, Random, Logistic, Softplus, Softmax)
@@ -249,6 +250,10 @@ def test_application():
     assert TestBrick.delegated_apply.inputs == ['w']
 
 
+def test_application_serialization():
+    assert id(cPickle.loads(cPickle.dumps(Linear.apply))) == id(Linear.apply)
+
+
 def test_apply():
     brick = TestBrick(0)
     assert TestBrick.apply(brick, [0]) == [0, 1]