Use objtools.registry

requirements.txt

@@ -0,0 +1 @@
+objtools>=0.1

stdqs/parsing/lookups.py

@@ -1,24 +1,32 @@
 from abc import ABCMeta, abstractmethod
-from stdqs.utils import Registry
+from objtools.registry import ClassRegistry
 import operator
 
 
-class LookupMetaclass(ABCMeta):
+class LookupRegistry(ClassRegistry):
 
-    def __new__(cls, name, *args, **kwargs):
-        newclass = ABCMeta.__new__(cls, name, *args, **kwargs)
-        if name != "Lookup":
-            register(newclass)
-        return newclass
+    def check_key(self, key):
+        assert isinstance(key, str), 'Lookup name must be a string.'
+
+    def check_value(self, value):
+        assert issubclass(value, Lookup), \
+            'Lookup should inherit from the Lookup abstract class.'
 
 
-class Lookup(metaclass=LookupMetaclass):
+registry = LookupRegistry()
+register = registry.register
+unregister = registry.unregister
+
+
+class LookupMetaclass(registry.metaclass, ABCMeta):
+    pass
+
+
+class Lookup(metaclass=LookupMetaclass, register=False):
     """
     A filtering operation: The "lt" in `field__lt=4`.
     """
 
-    lookup_name = None
-
     def __init__(self, lhs, rhs):
         self.lhs, self.rhs = lhs, rhs
 
@@ -55,54 +63,12 @@ def func_lookup(func, name=None):
         {
             '__module__': func_lookup.__module__,
             '__qualname__': class_name,
-            'lookup_name': name,
             'filter_obj': lambda self, obj: func(obj, self.rhs)
-        }
+        },
+        key=name,
     )
 
 
-class LookupRegistry(Registry):
-
-    def check_key(self, key):
-        assert isinstance(key, str), 'Lookup name must be a string.'
-
-    def check_value(self, value):
-        assert callable(getattr(value, 'filter_obj', None)), \
-            '{} should implement the filter_obj method.'.format(repr(value))
-
-    def register(self, key, value=None):
-        """
-        Register a lookup.
-        May be used as register(lookup_class) if the lookup has a defined name,
-        or as register(name, lookup_class) or register(lookup_class, name)
-        to set a custom name.
-        Can be used as a decorator on a Lookup if it has a defined name.
-        """
-        if value:
-            try:
-                return super().register(key, value)
-            except (KeyError, ValueError):
-                # Try the other way around
-                try:
-                    return super().register(value, key)
-                except (KeyError, ValueError):
-                    pass
-                raise
-
-        if not getattr(key, 'lookup_name', None):
-            raise KeyError(
-                'Lookup is missing a lookup name.'
-                'Set the lookup_name attribute or use register(name, lookup).'
-            )
-
-        super().register(key.lookup_name, key)
-
-
-registry = LookupRegistry()
-register = registry.register
-unregister = registry.unregister
-
-
 LessThanLookup = func_lookup(operator.lt)
 GreaterThanLookup = func_lookup(operator.gt)
 LessOrEqualLookup = func_lookup(operator.le, name='lte')

stdqs/parsing/transforms.py

@@ -1,18 +1,25 @@
-from stdqs.parsing.lookups import Lookup, LookupMetaclass, LookupRegistry
+from stdqs.parsing.lookups import Lookup, LookupRegistry
 from abc import ABCMeta, abstractmethod
 from collections.abc import Iterator
 
 
-class TransformMetaclass(LookupMetaclass):
+class TransformRegistry(LookupRegistry):
 
-    def __new__(cls, name, *args, **kwargs):
-        newclass = ABCMeta.__new__(cls, name, *args, **kwargs)
-        if name not in ("Transform", "GetterTransform"):
-            register(newclass)
-        return newclass
+    def check_value(self, value):
+        assert issubclass(value, Transform), \
+            'Transform must inherit from the Transform base class'
 
 
-class Transform(Lookup, metaclass=TransformMetaclass):
+registry = TransformRegistry()
+register = registry.register
+unregister = registry.unregister
+
+
+class TransformMetaclass(registry.metaclass, ABCMeta):
+    pass
+
+
+class Transform(metaclass=TransformMetaclass, register=False):
     """
     A special kind of lookup that also allows lookups on itself.
     For example, the "abs" in `field__abs__lt=2`.
@@ -20,7 +27,7 @@ class Transform(Lookup, metaclass=TransformMetaclass):
     """
 
     def __init__(self, lhs, rhs=None):
-        super().__init__(lhs, rhs)
+        self.lhs, self.rhs = lhs, rhs
 
     def filter_obj(self, obj):
         transformed = self.transform_obj(obj)
@@ -36,6 +43,13 @@ class Transform(Lookup, metaclass=TransformMetaclass):
         return NotImplemented.
         """
 
+    def __repr__(self):
+        return '{}({!r},{!r})'.format(
+            self.__class__.__name__,
+            self.lhs,
+            self.rhs,
+        )
+
 
 def func_transform(func, name=None):
     """
@@ -54,13 +68,13 @@ def func_transform(func, name=None):
         {
             '__module__': func_transform.__module__,
             '__qualname__': class_name,
-            'lookup_name': name,
             'transform_obj': lambda self, obj: func(obj)
-        }
+        },
+        key=name,
     )
 
 
-class GetterTransform(Transform):
+class GetterTransform(Transform, register=False):
     """
     A special Transform that fetches values from attributes, keys or methods.
     Should not be registered as a normal Transform.
@@ -84,18 +98,6 @@ class GetterTransform(Transform):
             return None
 
 
-class TransformRegistry(LookupRegistry):
-
-    def check_value(self, value):
-        super().check_value(value)
-        assert callable(getattr(value, 'transform_obj', None)), \
-            '{} should implement the transform_obj method.'.format(repr(value))
-
-
-registry = TransformRegistry()
-register = registry.register
-unregister = registry.unregister
-
 AbsoluteTransform = func_transform(abs)
 AsciiTransform = func_transform(ascii)
 BinaryTransform = func_transform(bin)

stdqs/queryset.py

@@ -1,6 +1,7 @@
 from collections.abc import Sequence, Collection, Iterator
+from objtools.registry import ClassRegistry
 from stdqs.exceptions import ObjectDoesNotExist, MultipleObjectsReturned
-from stdqs.utils import Registry, flatten
+from stdqs.utils import flatten
 from stdqs.parsing import QueryParser
 
 REPR_OUTPUT_SIZE = 20
@@ -165,7 +166,7 @@ class DictQuerySet(QuerySet):
         return flatten(self.collection)
 
 
-class QuerySetRegistry(Registry):
+class QuerySetRegistry(ClassRegistry):
 
     def check_key(self, key):
         assert isinstance(key, type), \

stdqs/utils.py

@@ -1,39 +1,6 @@
 from collections.abc import Mapping, Iterable
 
 
-class Registry(dict):
-
-    unregister = dict.__delitem__
-
-    def check_key(self, key):
-        pass
-
-    def check_value(self, value):
-        pass
-
-    def check(self, key, value):
-        try:
-            self.check_key(key)
-        except KeyError:
-            raise
-        except Exception as e:
-            raise KeyError(e.message)
-
-        try:
-            self.check_value(value)
-        except ValueError:
-            raise
-        except Exception as e:
-            raise ValueError(e.message)
-
-    def register(self, key, value):
-        self.__setitem__(key, value)
-
-    def __setitem__(self, key, value):
-        self.check(key, value)
-        super().__setitem__(key, value)
-
-
 def flatten(data):
     """
     Turns data structured in nested iterables into data suitable for filtering