Refactored generates decorator

sqlalchemy_utils/decorators.py

@@ -3,11 +3,64 @@ import itertools
 import sqlalchemy as sa
 import six
 
-generator_registry = defaultdict(list)
-listeners_registered = False
+
+class AttributeValueGenerator(object):
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.generator_registry = defaultdict(list)
+        self.listeners_registered = False
+
+    def generator_wrapper(self, func, attr):
+        def wrapper(self, *args, **kwargs):
+            return func(self, *args, **kwargs)
+
+        if isinstance(attr, six.string_types) and '.' in attr:
+            parts = attr.split('.')
+            self.generator_registry[parts[0]].append(wrapper)
+            wrapper.__generates__ = parts[1]
+        elif isinstance(attr, sa.orm.attributes.InstrumentedAttribute):
+            self.generator_registry[attr.class_.__name__].append(wrapper)
+            wrapper.__generates__ = attr
+        else:
+            wrapper.__generates__ = attr
+        return wrapper
+
+    def register_listeners(self):
+        if not self.listeners_registered:
+            sa.event.listen(
+                sa.orm.mapper,
+                'mapper_configured',
+                self.update_generator_registry
+            )
+            sa.event.listen(
+                sa.orm.session.Session,
+                'before_flush',
+                self.update_generated_properties
+            )
+            self.listeners_registered = True
+
+    def update_generator_registry(self, mapper, class_):
+        for value in class_.__dict__.values():
+            if hasattr(value, '__generates__'):
+                self.generator_registry[class_.__name__].append(value)
+
+    def update_generated_properties(self, session, ctx, instances):
+        for obj in itertools.chain(session.new, session.dirty):
+            class_ = obj.__class__.__name__
+            if class_ in self.generator_registry:
+                for func in self.generator_registry[class_]:
+                    attr = func.__generates__
+                    if not isinstance(attr, six.string_types):
+                        attr = attr.name
+                    setattr(obj, attr, func(obj))
 
 
-def generates(attr):
+generator = AttributeValueGenerator()
+
+
+def generates(attr, generator=generator):
     """
     Many times you may have generated property values. Usual cases include
     slugs from names or resized thumbnails from images.
@@ -75,54 +128,8 @@ def generates(attr):
             return article.name.lower().replace(' ', '-')
     """
 
-    register_listeners()
+    generator.register_listeners()
 
     def wraps(func):
-        def wrapper(self, *args, **kwargs):
-            return func(self, *args, **kwargs)
-
-        if isinstance(attr, six.string_types) and '.' in attr:
-            parts = attr.split('.')
-            generator_registry[parts[0]].append(wrapper)
-            wrapper.__generates__ = parts[1]
-        elif isinstance(attr, sa.orm.attributes.InstrumentedAttribute):
-            generator_registry[attr.class_.__name__].append(wrapper)
-            wrapper.__generates__ = attr
-        else:
-            wrapper.__generates__ = attr
-        return wrapper
+        return generator.generator_wrapper(func, attr)
     return wraps
-
-
-def register_listeners():
-    global listeners_registered
-
-    if not listeners_registered:
-        sa.event.listen(
-            sa.orm.mapper,
-            'mapper_configured',
-            update_generator_registry
-        )
-        sa.event.listen(
-            sa.orm.session.Session,
-            'before_flush',
-            update_generated_properties
-        )
-        listeners_registered = True
-
-
-def update_generator_registry(mapper, class_):
-    for value in class_.__dict__.values():
-        if hasattr(value, '__generates__'):
-            generator_registry[class_.__name__].append(value)
-
-
-def update_generated_properties(session, ctx, instances):
-    for obj in itertools.chain(session.new, session.dirty):
-        class_ = obj.__class__.__name__
-        if class_ in generator_registry:
-            for func in generator_registry[class_]:
-                attr = func.__generates__
-                if not isinstance(attr, six.string_types):
-                    attr = attr.name
-                setattr(obj, attr, func(obj))

tests/test_generates.py

@@ -1,13 +1,13 @@
-from collections import defaultdict
 import sqlalchemy as sa
-from sqlalchemy_utils import generates, decorators
+from sqlalchemy_utils import generates
+from sqlalchemy_utils.decorators import generator
 from tests import TestCase
 
 
 class GeneratesTestCase(TestCase):
     def teardown_method(self, method):
         TestCase.teardown_method(self, method)
-        decorators.generator_registry = defaultdict(list)
+        generator.reset()
 
     def test_generates_value_before_flush(self):
         article = self.Article()