newitem: redefine adaptor fields as staticmethods

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40933

scrapy/trunk/scrapy/contrib_exp/newitem/adaptors.py

@@ -1,24 +1,33 @@
-from functools import wraps
 from scrapy.utils.python import get_func_args
 
+def is_adaptor(func):
+    return callable(func) and 'adaptor_args' in get_func_args(func)
+
+class ItemAdaptorMetaClass(type):
+    def __new__(meta, name, bases, dct):
+        # defines adaptor fields as static methods
+        for key, func in dct.items():
+            if not key.startswith('_') and is_adaptor(func):
+                dct[key] = staticmethod(func)
+        return type.__new__(meta, name, bases, dct)
+
 
 class ItemAdaptor(object):
-    def __init__(self, response=None, item=None):
-        if item:
-            self.item_instance = item
-        else:
-            self.item_instance = self.item_class()
+    __metaclass__ = ItemAdaptorMetaClass
 
+    def __init__(self, response=None, item=None):
+        self.item_instance = item if item else self.item_class()
         self._response = response
         self._field_adaptors = self._get_field_adaptors()
 
     def _get_field_adaptors(self):
         def get_field_adaptor(field, cls):
-            if field in cls.__dict__:
-                return cls.__dict__[field]
-            else:
-                for class_ in cls.__bases__:
-                    return get_field_adaptor(field, class_)
+            func = getattr(cls, field, None)
+            if func:
+                return func
+
+            for class_ in cls.__bases__:
+                return get_field_adaptor(field, class_)
 
         fa = {}
         for field in self.item_instance._fields.keys():

scrapy/trunk/scrapy/tests/test_itemadaptor.py

@@ -1,5 +1,6 @@
 
 import unittest
+import string
 from scrapy.contrib_exp.newitem.adaptors import adaptor, ItemAdaptor
 from scrapy.contrib_exp.newitem import Item, StringField
 
@@ -53,17 +54,16 @@ class ItemAdaptorTest(unittest.TestCase):
         ia.name = 'marta'
         self.assertEqual(ia.name, 'Marta')
 
-    # FIXME: This test is fine but fails
-#     def test_inheritance_2(self):
-#         class ParentAdaptor(TestAdaptor):
-#             name = adaptor(lambda v, adaptor_args: v)
-# 
-#         class ChildAdaptor(ParentAdaptor):
-#             name = adaptor(lambda v: v.swapcase, ParentAdaptor.name)
-# 
-#         ia = ChildAdaptor()
-#         ia.name = 'marta'
-#         self.assertEqual(ia.name, 'mARTA')
+    def test_staticmethods(self):
+        class ParentAdaptor(TestAdaptor):
+            name = adaptor(lambda v, adaptor_args: v)
+
+        class ChildAdaptor(ParentAdaptor):
+            name = adaptor(ParentAdaptor.name, string.swapcase)
+
+        ia = ChildAdaptor()
+        ia.name = 'Marta'
+        self.assertEqual(ia.name, 'mARTA')