python - coding style: lightweight/simplest way to create instances supporting attribute assignment? -

i have create result object instance return complex values functions , wonder what's nice pythonic approach.

i aware of closely related attribute-assignment-to-built-in-object, asking why needs hack subclass workaround use 'object'. understand why already. asking instead if there existing support in standard library avoid using 'object' , subclass hack, either through existing class or function.

what's lightest, pythonic way instantiate instance supports attribute assignment?

i ok pointed right subclassing 'object' answer. it's no big deal - want know if had missed cleaner approach supported standard library or builtins.

sample of trying do:

try:     returnval = object()     returnval.foo = 1     returnval.bar = 2      print "\n\nsuccess %s" % (returnval), vars(returnval), "has __slots__:", hasattr(returnval, "__slots__"), "has __dict__:", hasattr(returnval, "__dict__")  except exception, e:     print "\n\nfailure %s:%s" % (returnval, e), "has __slots__:", hasattr(returnval, "__slots__"), "has __dict__:", hasattr(returnval, "__dict__") 

this fails, expected,

failure <object object @ 0x102c520a0>:'object' object has no attribute 'foo' has __slots__: false has __dict__: false 

i not surprised. 'object' bare stub, , not allow attribute assignment because has no __dict__.

instead have declare placeholder class. there cleaner way?

try:     class dummy(object): pass      returnval = dummy()     returnval.foo = 1     returnval.bar = 2     print "\n\nsuccess %s" % (returnval), vars(returnval), "has __slots__:", hasattr(returnval, "__slots__"), "has __dict__:", hasattr(returnval, "__dict__")  except exception, e:     print "\n\nfailure %s:%s" % (returnval, e), "has __slots__:", hasattr(returnval, "__slots__"), "has __dict__:", hasattr(returnval, "__dict__") 

this gives:

success <__main__.dummy object @ 0x102d5f810> {'foo': 1, 'bar': 2} has __slots__: false has __dict__: true 

using dummy/myclass approach avoids these problems, gives off mild code smell litter modules dummy classes.

things not work/are not satisfactory:

dictionaries. avoid if used dict instead, lose simple returnval.foo access.

attrdict implementations perhaps? come in 3rd party packages, not in standard lib.

mocks. not want using here, because not testing code , want exception thrown if returnval.foo not exist.

module/class attribute assignment. yes, assign attribute existing object in namespace, class or module declaration. assigning attributes singleton , successive function calls clobber each other.

a lightweight way use function container

>>> foo = lambda: 0 >>> foo.bar = 'bar' >>> foo.baz = 'baz' 

if making bunch of immutable objects same attributes collections.namedtuple more appropriate

>>> foo = namedtuple("foo", "bar, baz") >>> foo = foo('bar', 'baz') >>> foo.bar 'bar' >>> foo.baz 'baz'