non-strict mode

tasklocals/__init__.py

@@ -4,7 +4,14 @@
 from weakref import ref
 import asyncio
 
-__all__ = ['local']
+__all__ = ['local', 'NoTaskError']
+
+_default_local_dct = dict()
+
+
+class NoTaskError(RuntimeError):
+    pass
+
 
 class _localimpl:
     """A class managing task-local dicts"""
@@ -26,7 +33,7 @@ def get_dict(self):
         defined."""
         task = asyncio.Task.current_task(loop=self._loop)
         if task is None:
-            raise RuntimeError("No task is currently running")
+            raise NoTaskError("No task is currently running")
         return self.dicts[id(task)][1]
 
     def create_dict(self):
@@ -35,7 +42,7 @@ def create_dict(self):
         key = self.key
         task = asyncio.Task.current_task(loop=self._loop)
         if task is None:
-            raise RuntimeError("No task is currently running")
+            raise NoTaskError("No task is currently running")
         idt = id(task)
         def local_deleted(_, key=key):
             # When the localimpl is deleted, remove the task attribute.
@@ -60,25 +67,32 @@ def task_deleted(_, idt=idt):
 @contextmanager
 def _patch(self):
     impl = object.__getattribute__(self, '_local__impl')
+    strict = object.__getattribute__(self, '_strict')
     try:
         dct = impl.get_dict()
     except KeyError:
         dct = impl.create_dict()
         args, kw = impl.localargs
         self.__init__(*args, **kw)
+    except NoTaskError:
+        if strict:
+            raise
+        dct = _default_local_dct
     object.__setattr__(self, '__dict__', dct)
     yield
 
+
 class local:
-    __slots__ = '_local__impl', '__dict__'
+    __slots__ = '_local__impl', '__dict__', '_strict'
 
-    def __new__(cls, *args, loop=None, **kw):
+    def __new__(cls, *args, loop=None, strict=True, **kw):
         if (args or kw) and (cls.__init__ is object.__init__):
             raise TypeError("Initialization arguments are not supported")
         self = object.__new__(cls)
         impl = _localimpl(loop=loop)
         impl.localargs = (args, kw)
         object.__setattr__(self, '_local__impl', impl)
+        object.__setattr__(self, '_strict', strict)
         return self
 
     def __getattribute__(self, name):

tests/test_local.py

@@ -2,7 +2,7 @@
 import gc
 import asyncio
 import asyncio.test_utils
-from tasklocals import local
+from tasklocals import local, NoTaskError
 
 
 class LocalTests(unittest.TestCase):
@@ -16,8 +16,8 @@ def tearDown(self):
         self.loop.close()
         gc.collect()
 
-    def test_local(self):
-        mylocal = local(loop=self.loop)
+    def test_local(self, strict=True):
+        mylocal = local(loop=self.loop, strict=strict)
 
         log1 = []
         log2 = []
@@ -62,11 +62,20 @@ def task2():
         # ensure all task local values have been properly cleaned up
         self.assertEqual(object.__getattribute__(mylocal, '_local__impl').dicts, {})
 
+    def test_local_non_strict_mode(self):
+        self.test_local(strict=False)
+
     def test_local_outside_of_task(self):
         mylocal = local(loop=self.loop)
         try:
             mylocal.foo = 1
-            self.fail("RuntimeError has not been raised when tryint to use local object outside of a Task")
-        except RuntimeError:
+            self.fail("NoTaskError has not been raised when tryint to use local object outside of a Task")
+        except NoTaskError:
             pass
 
+    def test_local_outside_of_task_non_strict_mode(self):
+        mylocal = local(loop=self.loop, strict=False)
+        try:
+            mylocal.foo = 1
+        except NoTaskError:
+            self.fail("NoTaskError has been raised when tryint to use non-strict local object outside of a Task")