Prevent creating new attributes outside __init__

Question

I want to be able to create a class (in Python) that once initialized with __init__, does not accept new attributes, but accepts modifications of existing attri

Answer 1

I like the "Frozen" of Jochen Ritzel. The inconvenient is that the isfrozen variable then appears when printing a Class.__dict I went around this problem this way by creating a list of authorized attributes (similar to slots):

class Frozen(object):
    __List = []
    def __setattr__(self, key, value):
        setIsOK = False
        for item in self.__List:
            if key == item:
                setIsOK = True

        if setIsOK == True:
            object.__setattr__(self, key, value)
        else:
            raise TypeError( "%r has no attributes %r" % (self, key) )

class Test(Frozen):
    _Frozen__List = ["attr1","attr2"]
    def __init__(self):
        self.attr1   =  1
        self.attr2   =  1