are accessible)but not under public (all undeclared names are inaccessibleagainstudy this code on your own to get feel for how this works notice that this scheme adds an additional fourth level of state retention at the topbeyond that described in the preceding sectionthe test functions used by the lambdas are saved in an extra enclosing scope this example is coded to run under either python or ( or later)though it comes with caveat when run under (explained briefly in the file' docstring and expanded on after the code)""file access py ( xclass decorator with private and public attribute declarations controls external access to attributes stored on an instanceor inherited by it from its classes private declares attribute names that cannot be fetched or assigned outside the decorated classand public declares all the names that can caveatthis works in for explicitly named attributes only__x__ operator overloading methods implicitly run for built-in operations do not trigger either __getattr__ or __getattribute__ in new-style classes add __x__ methods here to intercept and delegate built-ins ""traceme false def trace(*args)if tracemeprint('[join(map(strargs)']'def accesscontrol(failif)def ondecorator(aclass)class oninstancedef __init__(self*args**kargs)self __wrapped aclass(*args**kargsdef __getattr__(selfattr)trace('get:'attrif failif(attr)raise typeerror('private attribute fetchattrelsereturn getattr(self __wrappedattrdef __setattr__(selfattrvalue)trace('set:'attrvalueif attr ='_oninstance__wrapped'self __dict__[attrvalue elif failif(attr)raise typeerror('private attribute changeattrelsesetattr(self __wrappedattrvaluereturn oninstance return ondecorator def private(*attributes)example"privateand "publicattributes