Improve the 'SelfAttribute' syntax.v1.1.0

Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>

2 files changed, 26 insertions, 18 deletions

diff --git a/factory/containers.py b/factory/containers.py
index fda9073..2f92f62 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 = declarations.ATTR_SPLITTER
+ATTR_SPLITTER = '__'
 
 
 class CyclicDefinitionError(Exception):
diff --git a/factory/declarations.py b/factory/declarations.py
index 08598e5..5fe427c 100644
--- a/factory/declarations.py
+++ b/factory/declarations.py
@@ -21,11 +21,6 @@
 # THE SOFTWARE.
 
 
-#: String for splitting an attribute name into a
-#: (subfactory_name, subfactory_field) tuple.
-ATTR_SPLITTER = '__'
-
-
 class OrderedDeclaration(object):
     """A factory declaration.
 
@@ -64,27 +59,37 @@ class LazyAttribute(OrderedDeclaration):
         return self.function(obj)
 
 
-def dig(obj, name):
-    """Try to retrieve the given attribute of an object, using ATTR_SPLITTER.
+class _UNSPECIFIED(object):
+    pass
+
 
-    If ATTR_SPLITTER is '__', dig(foo, 'a__b__c') is equivalent to foo.a.b.c.
+def deepgetattr(obj, name, default=_UNSPECIFIED):
+    """Try to retrieve the given attribute of an object, digging on '.'.
+
+    This is an extended getattr, digging deeper if '.' is found.
 
     Args:
         obj (object): the object of which an attribute should be read
         name (str): the name of an attribute to look up.
+        default (object): the default value to use if the attribute wasn't found
 
     Returns:
-        the attribute pointed to by 'name', according to ATTR_SPLITTER.
+        the attribute pointed to by 'name', splitting on '.'.
 
     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)
+    try:
+        if '.' in name:
+            attr, subname = name.split('.', 1)
+            return deepgetattr(getattr(obj, attr), subname, default)
+        else:
+            return getattr(obj, name)
+    except AttributeError:
+        if default is _UNSPECIFIED:
+            raise
+        else:
+            return default
 
 
 class SelfAttribute(OrderedDeclaration):
@@ -92,14 +97,17 @@ class SelfAttribute(OrderedDeclaration):
 
     Attributes:
         attribute_name (str): the name of the attribute to copy.
+        default (object): the default value to use if the attribute doesn't
+            exist.
     """
 
-    def __init__(self, attribute_name, *args, **kwargs):
+    def __init__(self, attribute_name, default=_UNSPECIFIED, *args, **kwargs):
         super(SelfAttribute, self).__init__(*args, **kwargs)
         self.attribute_name = attribute_name
+        self.default = default
 
     def evaluate(self, sequence, obj, containers=()):
-        return dig(obj, self.attribute_name)
+        return deepgetattr(obj, self.attribute_name, self.default)
 
 
 class Sequence(OrderedDeclaration):