From e3f334d42f391f3a247610b2c0a3c2226679a1d9 Mon Sep 17 00:00:00 2001
From: Lukas Prediger <lukas.prediger@rwth-aachen.de>
Date: Sun, 17 Jun 2018 19:34:48 +0200
Subject: [PATCH 1/2] Fix for pulse registration in Serialziable.__init__

---
 qctoolkit/serialization.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qctoolkit/serialization.py b/qctoolkit/serialization.py
index dcc57d529..ef903dde1 100644
--- a/qctoolkit/serialization.py
+++ b/qctoolkit/serialization.py
@@ -358,7 +358,7 @@ def __init__(self, identifier: Optional[str]=None, registration: weakref.WeakVal
             raise ValueError("Identifier must not be empty.")
         self.__identifier = identifier
 
-        if identifier and registration:
+        if identifier and registration is not None:
             if identifier in registration:
                 raise RuntimeError('Pulse with name already exists', identifier)
             else:

From 789309a1683278086ae17f8d18a21da3c12e6d48 Mon Sep 17 00:00:00 2001
From: Lukas Prediger <lukas.prediger@rwth-aachen.de>
Date: Sun, 17 Jun 2018 19:40:49 +0200
Subject: [PATCH 2/2] PulseStorage can be conveniently replace default pulse
 registration.

Added get_default_pulse_registration() method to query current default pulse registration.
Added method PulseStorage.as_default_registry(), a context manager method that causes the PulseStorage object to replace the current default pulse registration for the duration of a "with:" block.
Added method PulseStorage.set_to_default_registry() which permanently sets the PulseStorage object as the default pulse registration.
---
 qctoolkit/serialization.py   | 19 +++++++++++++++++++
 tests/serialization_tests.py | 15 ++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/qctoolkit/serialization.py b/qctoolkit/serialization.py
index ef903dde1..409df9906 100644
--- a/qctoolkit/serialization.py
+++ b/qctoolkit/serialization.py
@@ -17,6 +17,7 @@
 import json
 import weakref
 import warnings
+from contextlib import contextmanager
 
 from qctoolkit.utils.types import DocStringABCMeta
 
@@ -319,6 +320,10 @@ def __new__(mcs, name, bases, dct):
 default_pulse_registration = weakref.WeakValueDictionary()
 
 
+def get_default_pulse_registration() -> Union[weakref.WeakKeyDictionary, 'PulseStorage']:
+    return default_pulse_registration
+
+
 class Serializable(metaclass=SerializableMeta):
     """Any object that can be converted into a serialized representation for storage and back.
 
@@ -672,6 +677,20 @@ def clear(self) -> None:
     def __del__(self) -> None:
         self.flush()
 
+    @contextmanager
+    def as_default_registry(self) -> Any:
+        global default_pulse_registration
+        previous_registration = default_pulse_registration
+        default_pulse_registration = self
+        try:
+            yield self
+        finally:
+            default_pulse_registration = previous_registration
+
+    def set_to_default_registry(self) -> None:
+        global default_pulse_registration
+        default_pulse_registration = self
+
 
 class JSONSerializableDecoder(json.JSONDecoder):
 
diff --git a/tests/serialization_tests.py b/tests/serialization_tests.py
index 319faf22a..38d5378fd 100644
--- a/tests/serialization_tests.py
+++ b/tests/serialization_tests.py
@@ -12,7 +12,8 @@
 from typing import Optional, Any
 
 from qctoolkit.serialization import FilesystemBackend, CachingBackend, Serializable, JSONSerializableEncoder,\
-    ZipFileBackend, AnonymousSerializable, DictBackend, PulseStorage, JSONSerializableDecoder, Serializer
+    ZipFileBackend, AnonymousSerializable, DictBackend, PulseStorage, JSONSerializableDecoder, Serializer, get_default_pulse_registration
+
 
 from tests.serialization_dummies import DummyStorageBackend
 
@@ -506,6 +507,18 @@ def test_flush_on_destroy_object(self) -> None:
 
         self.assertIn('my_id_1', backend.stored_items)
 
+    def test_as_default_registry(self) -> None:
+        prev_reg = get_default_pulse_registration()
+        pulse_storage = PulseStorage(DummyStorageBackend())
+        with pulse_storage.as_default_registry():
+            self.assertIs(get_default_pulse_registration(), pulse_storage)
+        self.assertIs(get_default_pulse_registration(), prev_reg)
+
+    def test_set_to_default_registry(self) -> None:
+        pulse_storage = PulseStorage(DummyStorageBackend())
+        pulse_storage.set_to_default_registry()
+        self.assertIs(get_default_pulse_registration(), pulse_storage)
+
 
 class JSONSerializableDecoderTests(unittest.TestCase):
     def test_filter_serializables(self):