Allow calling getanno with a default value. Failure is still the defa…

…ult behavior.

PiperOrigin-RevId: 199349592

tensorflow/contrib/autograph/pyct/anno.py

@@ -46,8 +46,15 @@ class Basic(NoValue):
       '`name_map` allows renaming symbols.')
 
 
-def getanno(node, key, field_name='___pyct_anno'):
-  return getattr(node, field_name)[key]
+FAIL = object()
+
+
+def getanno(node, key, default=FAIL, field_name='___pyct_anno'):
+  if (default is FAIL or
+      (hasattr(node, field_name) and getattr(node, field_name)[key])):
+    return getattr(node, field_name)[key]
+  else:
+    return default
 
 
 def hasanno(node, key, field_name='___pyct_anno'):
@@ -73,5 +80,9 @@ def delanno(node, key, field_name='___pyct_anno'):
 
 
 def copyanno(from_node, to_node, key, field_name='___pyct_anno'):
-  if hasanno(from_node, key, field_name):
-    setanno(to_node, key, getanno(from_node, key, field_name), field_name)
+  if hasanno(from_node, key, field_name=field_name):
+    setanno(
+        to_node,
+        key,
+        getanno(from_node, key, field_name=field_name),
+        field_name=field_name)

tensorflow/contrib/autograph/pyct/anno_test.py

@@ -44,6 +44,7 @@ def test_basic(self):
     self.assertFalse(anno.hasanno(node, 'foo'))
     with self.assertRaises(AttributeError):
       anno.getanno(node, 'foo')
+    self.assertIsNone(anno.getanno(node, 'foo', default=None))
 
   def test_copyanno(self):
     node_1 = ast.Name()