Add some checks for "own" attributes in __getattr__. Fixes infinite recursion issues when factory does something crazy like raising AttributeError. Fixes ionelmc#3.

Author: ionelmc

src/lazy_object_proxy/simple.py

@@ -72,6 +72,8 @@ def __new__(cls, name, bases, dictionary):
 
 
 class Proxy(with_metaclass(_ProxyMetaType)):
+    __factory__ = None
+
     def __init__(self, factory):
         self.__dict__['__factory__'] = factory
 
@@ -122,7 +124,10 @@ def __setattr__(self, name, value):
             setattr(self.__wrapped__, name, value)
 
     def __getattr__(self, name):
-        return getattr(self.__wrapped__, name)
+        if name in ('__wrapped__', '__factory__'):
+            raise AttributeError(name)
+        else:
+            return getattr(self.__wrapped__, name)
 
     def __delattr__(self, name):
         if hasattr(type(self), name):

src/lazy_object_proxy/slots.py

@@ -182,7 +182,10 @@ def __setattr__(self, name, value, __setattr__=object.__setattr__):
             setattr(self.__wrapped__, name, value)
 
     def __getattr__(self, name):
-        return getattr(self.__wrapped__, name)
+        if name in ('__wrapped__', '__factory__'):
+            raise AttributeError(name)
+        else:
+            return getattr(self.__wrapped__, name)
 
     def __delattr__(self, name, __delattr__=object.__delattr__):
         if hasattr(type(self), name):

tests/test_lazy_object_proxy.py

@@ -1598,6 +1598,15 @@ class Foo(object):
     del proxy.__wrapped__
 
 
+def test_raise_attribute_error(lazy_object_proxy):
+    def foo():
+        raise AttributeError("boom!")
+    proxy = lazy_object_proxy.Proxy(foo)
+    pytest.raises(AttributeError, str, proxy)
+    pytest.raises(AttributeError, lambda: proxy.__wrapped__)
+    assert proxy.__factory__ is foo
+
+
 def test_new(lazy_object_proxy):
     a = lazy_object_proxy.Proxy.__new__(lazy_object_proxy.Proxy)
     b = lazy_object_proxy.Proxy.__new__(lazy_object_proxy.Proxy)