From 11fead308ce398d8b1a1641cc1ba8450fbb93c41 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:23:36 +0200
Subject: add a draft of the registry wrapper class

---
 pint/registry.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/pint/registry.py b/pint/registry.py
index 4428ad4..ff4df84 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2323,3 +2323,17 @@ class LazyRegistry:
     def __call__(self, *args, **kwargs):
         self.__init()
         return self(*args, **kwargs)
+
+
+class ApplicationRegistry:
+    def __init__(self, registry):
+        self._registry = registry
+
+    def set(self, new_registry):
+        self._registry = new_registry
+
+    def __getattr__(self, name):
+        return getattr(self._registry, name)
+
+    def __dir__(self):
+        return dir(self._registry)
-- 
cgit v1.2.1


From 0b5d917caf90657d05f1dd38a5af817fbf00a82d Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:24:39 +0200
Subject: manually override a few dunder methods

---
 pint/registry.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pint/registry.py b/pint/registry.py
index ff4df84..d94bb4f 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2337,3 +2337,15 @@ class ApplicationRegistry:
 
     def __dir__(self):
         return dir(self._registry)
+
+    def __getitem__(self, item):
+        return self._registry[item]
+
+    def __call__(self, *args, **kwargs):
+        return self._registry(*args, **kwargs)
+
+    def __contains__(self, item):
+        return self._registry.__contains__(item)
+
+    def __iter__(self):
+        return iter(self._registry)
-- 
cgit v1.2.1


From 619c8e5f8cf7f4b2a3f9b2bf7c890b98a14ccb81 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:26:29 +0200
Subject: add the application registry object

---
 pint/__init__.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pint/__init__.py b/pint/__init__.py
index 3db4bb5..5788d1c 100644
--- a/pint/__init__.py
+++ b/pint/__init__.py
@@ -25,7 +25,7 @@ from .errors import (  # noqa: F401
 from .formatting import formatter
 from .measurement import Measurement
 from .quantity import Quantity
-from .registry import LazyRegistry, UnitRegistry
+from .registry import ApplicationRegistry, LazyRegistry, UnitRegistry
 from .unit import Unit
 from .util import logger, pi_theorem
 
@@ -48,6 +48,7 @@ _DEFAULT_REGISTRY = LazyRegistry()
 
 #: Registry used for unpickling operations.
 _APP_REGISTRY = _DEFAULT_REGISTRY
+application_registry = ApplicationRegistry(_DEFAULT_REGISTRY)
 
 
 def _unpickle(cls, *args):
-- 
cgit v1.2.1


From 08abfd0ede1d720f501730bd8d09c0a7b88e5135 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:35:14 +0200
Subject: reimplement `get_application_registry` and `set_application_registry`

---
 pint/__init__.py | 10 +++-------
 pint/registry.py |  5 +++++
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/pint/__init__.py b/pint/__init__.py
index 5788d1c..0f7d2f2 100644
--- a/pint/__init__.py
+++ b/pint/__init__.py
@@ -27,7 +27,7 @@ from .measurement import Measurement
 from .quantity import Quantity
 from .registry import ApplicationRegistry, LazyRegistry, UnitRegistry
 from .unit import Unit
-from .util import logger, pi_theorem
+from .util import logger, pi_theorem  # noqa: F401
 
 try:
     from importlib.metadata import version
@@ -101,11 +101,7 @@ def set_application_registry(registry):
     ----------
     registry : pint.UnitRegistry
     """
-    if not isinstance(registry, (LazyRegistry, UnitRegistry)):
-        raise TypeError("Expected UnitRegistry; got %s" % type(registry))
-    global _APP_REGISTRY
-    logger.debug("Changing app registry from %r to %r.", _APP_REGISTRY, registry)
-    _APP_REGISTRY = registry
+    application_registry.set(registry)
 
 
 def get_application_registry():
@@ -117,7 +113,7 @@ def get_application_registry():
     -------
     pint.UnitRegistry
     """
-    return _APP_REGISTRY
+    return application_registry
 
 
 def test():
diff --git a/pint/registry.py b/pint/registry.py
index d94bb4f..3d3ee91 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2330,6 +2330,11 @@ class ApplicationRegistry:
         self._registry = registry
 
     def set(self, new_registry):
+        if not isinstance(new_registry, (LazyRegistry, UnitRegistry)):
+            raise TypeError("Expected UnitRegistry; got %s" % type(new_registry))
+        logger.debug(
+            "Changing app registry from %r to %r.", self._registry, new_registry
+        )
         self._registry = new_registry
 
     def __getattr__(self, name):
-- 
cgit v1.2.1


From 735eb3a016b9d128ed75594b4e7ee1a52f8419d2 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:49:27 +0200
Subject: assign _APP_REGISTRY to the new name

---
 pint/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pint/__init__.py b/pint/__init__.py
index 0f7d2f2..d652f5a 100644
--- a/pint/__init__.py
+++ b/pint/__init__.py
@@ -47,8 +47,8 @@ except Exception:  # pragma: no cover
 _DEFAULT_REGISTRY = LazyRegistry()
 
 #: Registry used for unpickling operations.
-_APP_REGISTRY = _DEFAULT_REGISTRY
 application_registry = ApplicationRegistry(_DEFAULT_REGISTRY)
+_APP_REGISTRY = application_registry
 
 
 def _unpickle(cls, *args):
-- 
cgit v1.2.1


From 816ee0974d2f688c8e3048beb777446b12825275 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:50:13 +0200
Subject: allow setting the object returned by `get_application_registry`

---
 pint/registry.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pint/registry.py b/pint/registry.py
index 3d3ee91..d848feb 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2330,6 +2330,9 @@ class ApplicationRegistry:
         self._registry = registry
 
     def set(self, new_registry):
+        if isinstance(new_registry, type(self)):
+            new_registry = new_registry._registry
+
         if not isinstance(new_registry, (LazyRegistry, UnitRegistry)):
             raise TypeError("Expected UnitRegistry; got %s" % type(new_registry))
         logger.debug(
-- 
cgit v1.2.1


From 9de66105bf871f5f5f976eea837d48bca238873e Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Thu, 5 Aug 2021 19:51:02 +0200
Subject: don't type check the value returned by `get_application_registry()`

---
 pint/testsuite/test_application_registry.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pint/testsuite/test_application_registry.py b/pint/testsuite/test_application_registry.py
index 59c3521..97ce3fb 100644
--- a/pint/testsuite/test_application_registry.py
+++ b/pint/testsuite/test_application_registry.py
@@ -102,7 +102,7 @@ class TestCustomApplicationRegistry:
         cls.ureg.define("foo = []")
         cls.ureg.define("bar = foo / 2")
         set_application_registry(cls.ureg)
-        assert get_application_registry() is cls.ureg
+        # assert get_application_registry() is cls.ureg
 
     @classmethod
     def teardown_class(cls):
-- 
cgit v1.2.1


From 2e011924e3ac8815cced2556615e83982402ef2f Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Fri, 6 Aug 2021 00:05:54 +0200
Subject: save the actual registry in shared registry objects

---
 pint/registry.py | 3 +++
 pint/util.py     | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/pint/registry.py b/pint/registry.py
index d848feb..892a075 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2329,6 +2329,9 @@ class ApplicationRegistry:
     def __init__(self, registry):
         self._registry = registry
 
+    def get(self):
+        return self._registry
+
     def set(self, new_registry):
         if isinstance(new_registry, type(self)):
             new_registry = new_registry._registry
diff --git a/pint/util.py b/pint/util.py
index 18474ec..a2f34d6 100644
--- a/pint/util.py
+++ b/pint/util.py
@@ -820,7 +820,7 @@ class SharedRegistryObject:
             # UnitRegistry._init_dynamic_classes
             from . import _APP_REGISTRY
 
-            inst._REGISTRY = _APP_REGISTRY
+            inst._REGISTRY = _APP_REGISTRY.get()
         return inst
 
     def _check(self, other) -> bool:
-- 
cgit v1.2.1


From 5fea75380d434b7f5e407aa2d8420db78332066c Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Sun, 8 Aug 2021 01:28:12 +0200
Subject: remove _APP_DIR

---
 pint/__init__.py | 9 ++++-----
 pint/util.py     | 4 ++--
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/pint/__init__.py b/pint/__init__.py
index d652f5a..9f126d5 100644
--- a/pint/__init__.py
+++ b/pint/__init__.py
@@ -48,7 +48,6 @@ _DEFAULT_REGISTRY = LazyRegistry()
 
 #: Registry used for unpickling operations.
 application_registry = ApplicationRegistry(_DEFAULT_REGISTRY)
-_APP_REGISTRY = application_registry
 
 
 def _unpickle(cls, *args):
@@ -73,24 +72,24 @@ def _unpickle(cls, *args):
         # We need to make sure that this happens before using.
         if isinstance(arg, UnitsContainer):
             for name in arg:
-                _APP_REGISTRY.parse_units(name)
+                application_registry.parse_units(name)
 
     return cls(*args)
 
 
 def _unpickle_quantity(cls, *args):
     """Rebuild quantity upon unpickling using the application registry."""
-    return _unpickle(_APP_REGISTRY.Quantity, *args)
+    return _unpickle(application_registry.Quantity, *args)
 
 
 def _unpickle_unit(cls, *args):
     """Rebuild unit upon unpickling using the application registry."""
-    return _unpickle(_APP_REGISTRY.Unit, *args)
+    return _unpickle(application_registry.Unit, *args)
 
 
 def _unpickle_measurement(cls, *args):
     """Rebuild measurement upon unpickling using the application registry."""
-    return _unpickle(_APP_REGISTRY.Measurement, *args)
+    return _unpickle(application_registry.Measurement, *args)
 
 
 def set_application_registry(registry):
diff --git a/pint/util.py b/pint/util.py
index a2f34d6..46105f4 100644
--- a/pint/util.py
+++ b/pint/util.py
@@ -818,9 +818,9 @@ class SharedRegistryObject:
         if not hasattr(cls, "_REGISTRY"):
             # Base class, not subclasses dynamically by
             # UnitRegistry._init_dynamic_classes
-            from . import _APP_REGISTRY
+            from . import application_registry
 
-            inst._REGISTRY = _APP_REGISTRY.get()
+            inst._REGISTRY = application_registry.get()
         return inst
 
     def _check(self, other) -> bool:
-- 
cgit v1.2.1


From 7e53f25d74b1113c3b0c55ad506edf5f75c40cdc Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Sun, 8 Aug 2021 01:44:33 +0200
Subject: use the public method

---
 pint/registry.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pint/registry.py b/pint/registry.py
index 892a075..c6bdcdc 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2334,7 +2334,7 @@ class ApplicationRegistry:
 
     def set(self, new_registry):
         if isinstance(new_registry, type(self)):
-            new_registry = new_registry._registry
+            new_registry = new_registry.get()
 
         if not isinstance(new_registry, (LazyRegistry, UnitRegistry)):
             raise TypeError("Expected UnitRegistry; got %s" % type(new_registry))
-- 
cgit v1.2.1


From 6d1f192572b4f0c1f8cef66335ef3b9f367193f9 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Sun, 8 Aug 2021 01:46:53 +0200
Subject: properly isolate the application registry using fixtures

---
 pint/testsuite/test_application_registry.py | 51 ++++++++++++++---------------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/pint/testsuite/test_application_registry.py b/pint/testsuite/test_application_registry.py
index 97ce3fb..fbd8026 100644
--- a/pint/testsuite/test_application_registry.py
+++ b/pint/testsuite/test_application_registry.py
@@ -5,6 +5,7 @@ import pickle
 import pytest
 
 from pint import (
+    ApplicationRegistry,
     Measurement,
     Quantity,
     UndefinedUnitError,
@@ -16,6 +17,14 @@ from pint import (
 from pint.testsuite import helpers
 
 
+@pytest.fixture
+def isolate_application_registry(monkeypatch):
+    import pint
+
+    new = ApplicationRegistry(UnitRegistry())
+    monkeypatch.setattr(pint, "application_registry", new)
+
+
 class TestDefaultApplicationRegistry:
     @helpers.allprotos
     def test_unit(self, protocol):
@@ -94,20 +103,16 @@ class TestDefaultApplicationRegistry:
             pickle.loads(b)
 
 
-class TestCustomApplicationRegistry:
-    @classmethod
-    def setup_class(cls):
-        cls.ureg_bak = get_application_registry()
-        cls.ureg = UnitRegistry(None)
-        cls.ureg.define("foo = []")
-        cls.ureg.define("bar = foo / 2")
-        set_application_registry(cls.ureg)
-        # assert get_application_registry() is cls.ureg
-
-    @classmethod
-    def teardown_class(cls):
-        set_application_registry(cls.ureg_bak)
+@pytest.fixture
+def custom_registry(isolate_application_registry):
+    ureg = UnitRegistry(None)
+    ureg.define("foo = []")
+    ureg.define("bar = foo / 2")
+    set_application_registry(ureg)
+
 
+@pytest.mark.usefixtures("custom_registry")
+class TestCustomApplicationRegistry:
     @helpers.allprotos
     def test_unit(self, protocol):
         u = Unit("foo")
@@ -158,6 +163,7 @@ class TestCustomApplicationRegistry:
         assert str(m.units) == "foo"
 
 
+@pytest.mark.usefixtures("isolate_application_registry")
 class TestSwapApplicationRegistry:
     """Test that the constructors of Quantity, Unit, and Measurement capture
     the registry that is set as the application registry at creation time
@@ -170,19 +176,12 @@ class TestSwapApplicationRegistry:
 
     """
 
-    @classmethod
-    def setup_class(cls):
-        cls.ureg_bak = get_application_registry()
-        cls.ureg1 = UnitRegistry(None)
-        cls.ureg1.define("foo = [dim1]")
-        cls.ureg1.define("bar = foo / 2")
-        cls.ureg2 = UnitRegistry(None)
-        cls.ureg2.define("foo = [dim2]")
-        cls.ureg2.define("bar = foo / 3")
-
-    @classmethod
-    def teardown_class(cls):
-        set_application_registry(cls.ureg_bak)
+    ureg1 = UnitRegistry(None)
+    ureg1.define("foo = [dim1]")
+    ureg1.define("bar = foo / 2")
+    ureg2 = UnitRegistry(None)
+    ureg2.define("foo = [dim2]")
+    ureg2.define("bar = foo / 3")
 
     @helpers.allprotos
     def test_quantity_1arg(self, protocol):
-- 
cgit v1.2.1


From 7b8bc3e13482102f50d27dcd68bca39f296ac361 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Sun, 8 Aug 2021 11:09:04 +0200
Subject: add a test checking that saved registries are properly updated

---
 pint/testsuite/test_application_registry.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pint/testsuite/test_application_registry.py b/pint/testsuite/test_application_registry.py
index fbd8026..2ec349c 100644
--- a/pint/testsuite/test_application_registry.py
+++ b/pint/testsuite/test_application_registry.py
@@ -258,3 +258,15 @@ class TestSwapApplicationRegistry:
         assert m1.to("bar").error.magnitude == 2
         assert m2.to("bar").error.magnitude == 3
         assert m3.to("bar").error.magnitude == 3
+
+
+@pytest.mark.usefixtures("isolate_application_registry")
+def test_update_saved_registries():
+    ureg1 = get_application_registry()
+    ureg2 = get_application_registry()
+
+    new = UnitRegistry()
+    new.define("foo = []")
+    set_application_registry(new)
+
+    assert ureg1.Unit("foo") == ureg2.Unit("foo")
-- 
cgit v1.2.1


From c135b5c995f058ade8c98298cbe7061b4e50675a Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Sat, 14 Aug 2021 14:50:33 +0200
Subject: add docstrings to the application registry

---
 pint/registry.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/pint/registry.py b/pint/registry.py
index c6bdcdc..f53becc 100644
--- a/pint/registry.py
+++ b/pint/registry.py
@@ -2326,13 +2326,27 @@ class LazyRegistry:
 
 
 class ApplicationRegistry:
+    """A wrapper class used to distribute changes to the application registry."""
+
     def __init__(self, registry):
         self._registry = registry
 
     def get(self):
+        """Get the wrapped registry"""
         return self._registry
 
     def set(self, new_registry):
+        """Set the new registry
+
+        Parameters
+        ----------
+        new_registry : ApplicationRegistry or LazyRegistry or UnitRegistry
+            The new registry.
+
+        See Also
+        --------
+        set_application_registry
+        """
         if isinstance(new_registry, type(self)):
             new_registry = new_registry.get()
 
-- 
cgit v1.2.1


From 1a8e7e7d8e0ceb77d06e93dd1d9e8828bfa84921 Mon Sep 17 00:00:00 2001
From: Keewis <keewis@posteo.de>
Date: Fri, 20 Aug 2021 11:48:45 +0200
Subject: update CHANGES

---
 CHANGES | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGES b/CHANGES
index 477aa09..e53cc5b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -16,6 +16,7 @@ Pint Changelog
 - Fix string formatting of numpy array scalars
 - Fix default format for Measurement class (Issue #1300)
 - Fix parsing of pretty units with same exponents but different sign. (Issue #1360)
+- Convert the application registry to a wrapper object (Issue #1365)
 
 ### Breaking Changes
 
-- 
cgit v1.2.1