From 2a1138550b3220b6f8cd23bae5fed03f0fb448cf Mon Sep 17 00:00:00 2001
From: Raphaël Barrois <raphael.barrois@polytechnique.org>
Date: Fri, 24 Feb 2012 00:07:53 +0100
Subject: Allow using '__' in factory.SelfAttribute.
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Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>
---
 factory/containers.py      |  2 +-
 factory/declarations.py    | 33 ++++++++++++++++++++++++++++++---
 tests/test_declarations.py | 41 ++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 71 insertions(+), 5 deletions(-)

diff --git a/factory/containers.py b/factory/containers.py
index dd11f5f..ef97548 100644
--- a/factory/containers.py
+++ b/factory/containers.py
@@ -26,7 +26,7 @@ from factory import declarations
 
 #: String for splitting an attribute name into a
 #: (subfactory_name, subfactory_field) tuple.
-ATTR_SPLITTER = '__'
+ATTR_SPLITTER = declarations.ATTR_SPLITTER
 
 
 class CyclicDefinitionError(Exception):
diff --git a/factory/declarations.py b/factory/declarations.py
index 0ce7071..60425c3 100644
--- a/factory/declarations.py
+++ b/factory/declarations.py
@@ -20,6 +20,12 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
+
+#: String for splitting an attribute name into a
+#: (subfactory_name, subfactory_field) tuple.
+ATTR_SPLITTER = '__'
+
+
 class OrderedDeclaration(object):
     """A factory declaration.
 
@@ -58,6 +64,29 @@ class LazyAttribute(OrderedDeclaration):
         return self.function(obj)
 
 
+def dig(obj, name):
+    """Try to retrieve the given attribute of an object, using ATTR_SPLITTER.
+
+    If ATTR_SPLITTER is '__', dig(foo, 'a__b__c') is equivalent to foo.a.b.c.
+
+    Args:
+        obj (object): the object of which an attribute should be read
+        name (str): the name of an attribute to look up.
+
+    Returns:
+        the attribute pointed to by 'name', according to ATTR_SPLITTER.
+
+    Raises:
+        AttributeError: if obj has no 'name' attribute.
+    """
+    may_split = (ATTR_SPLITTER in name and not name.startswith(ATTR_SPLITTER))
+    if may_split and not hasattr(obj, name):
+        attr, subname = name.split(ATTR_SPLITTER, 1)
+        return dig(getattr(obj, attr), subname)
+    else:
+        return getattr(obj, name)
+
+
 class SelfAttribute(OrderedDeclaration):
     """Specific OrderedDeclaration copying values from other fields.
 
@@ -70,9 +99,7 @@ class SelfAttribute(OrderedDeclaration):
         self.attribute_name = attribute_name
 
     def evaluate(self, sequence, obj, containers=()):
-        # TODO(rbarrois): allow the use of ATTR_SPLITTER to fetch fields of
-        # subfactories.
-        return getattr(obj, self.attribute_name)
+        return dig(obj, self.attribute_name)
 
 
 class Sequence(OrderedDeclaration):
diff --git a/tests/test_declarations.py b/tests/test_declarations.py
index dcee38b..0fcdf10 100644
--- a/tests/test_declarations.py
+++ b/tests/test_declarations.py
@@ -22,12 +22,51 @@
 
 import unittest
 
-from factory.declarations import OrderedDeclaration, Sequence
+from factory.declarations import dig, OrderedDeclaration, Sequence
 
 class OrderedDeclarationTestCase(unittest.TestCase):
     def test_errors(self):
         decl = OrderedDeclaration()
         self.assertRaises(NotImplementedError, decl.evaluate, None, {})
 
+
+class DigTestCase(unittest.TestCase):
+    class MyObj(object):
+        def __init__(self, n):
+            self.n = n
+
+    def test_parentattr(self):
+        obj = self.MyObj(1)
+        obj.a__b__c = self.MyObj(2)
+        obj.a = self.MyObj(3)
+        obj.a.b = self.MyObj(4)
+        obj.a.b.c = self.MyObj(5)
+
+        self.assertEqual(2, dig(obj, 'a__b__c').n)
+
+    def test_private(self):
+        obj = self.MyObj(1)
+        self.assertEqual(obj.__class__, dig(obj, '__class__'))
+
+    def test_chaining(self):
+        obj = self.MyObj(1)
+        obj.a = self.MyObj(2)
+        obj.a__c = self.MyObj(3)
+        obj.a.b = self.MyObj(4)
+        obj.a.b.c = self.MyObj(5)
+
+        self.assertEqual(2, dig(obj, 'a').n)
+        self.assertRaises(AttributeError, dig, obj, 'b')
+        self.assertEqual(2, dig(obj, 'a__n'))
+        self.assertEqual(3, dig(obj, 'a__c').n)
+        self.assertRaises(AttributeError, dig, obj, 'a__c__n')
+        self.assertRaises(AttributeError, dig, obj, 'a__d')
+        self.assertEqual(4, dig(obj, 'a__b').n)
+        self.assertEqual(4, dig(obj, 'a__b__n'))
+        self.assertEqual(5, dig(obj, 'a__b__c').n)
+        self.assertEqual(5, dig(obj, 'a__b__c__n'))
+
+
+
 if __name__ == '__main__':
     unittest.main()
-- 
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