Hi Justin, Awesome! Thank you so much! I will definitely try our your instruction tonight.
Matthew, On Fri, Sep 13, 2013 at 2:42 PM, Justin Israel <[email protected]>wrote: > I'm not 100% clear on the intent of the code, but if you are trying to > discourage users from replacing existing attributes on the instance, you > could try and catch it all in the __setattr__ of the class: > > class Bunch(object): > def __init__(self, *args, **kwargs): > for key, value in kwargs.items(): > self.__testAttr(key) > setattr(self, key, value) > > def __setattr__(self, key, value): > self.__testAttr(key) > super(Bunch, self).__setattr__(key, value) > > def __testAttr(self, key): > if hasattr(self, key): > raise AttributeError("API conflict: '%s' is part " \ > "of the '%s' API" % (key, self)) > > def pretty(self): > text = "" > for key, value in self.__dict__.items(): > text += "%s: %s\n" % (key, value) > return text > > In this example, we just do our check any time they try and set an > attribute on the instance. In python you can never fully prevent these > types of things, since the language is dynamic and interpreted. But this at > least prevents the most direct approaches. > One thing I notice in your example is that once someone sets a new > attribute on the class, they can never change it again, since it will then > fail the test the next time. If you want the functionality of allowing > existing attributes that the user has added to be changed, you would need > to keep track of them in a list of approved attributes. > > > On Sep 14, 2013, at 2:33 AM, matthew park wrote: > > Hello there, > > I am learning masking case when an object is instanced in a class and if > the name of the object and > method's name is same, Type error is raised. > > the code is > > class Bunch(object): > def __init__(self, *args, **kwargs): > for key, value in kwargs.items(): > if hasattr(self, key): > raise AttributeError("API conflict: '%s' is part of the > '%s' API" % (key, self)) > else: > setattr(self, key, value) > > def pretty(self): > text = "" > for key, value in self.__dict__.items(): > text += "%s: %s\n" % (key, value) > return text > > if __name__ == "__main__": > b = Bunch(pretty=True) > > > The point is I don't know how to set up' *bunch.pretty = True* ' to > prove mistake in the following sentences below. > There, the code triggered a TypeError exception because the Bunch > class's pretty() method was *masked* by a data attribute on the > instance, which we then attempted to call. While the Bunch class now > protects this from happening during object instantiation, there is nothing > to prevent you from masking the pretty() method simply by setting > *bunch.pretty > = True* after creating an instance. > > > Can you give me an example code how to prove nothing to prevent the code > from masking pretty() method > simple by setting *bunch.pretty=True*? > > > Thank you very much for your help! > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- > You received this message because you are subscribed to the Google Groups > "Python Programming for Autodesk Maya" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Python Programming for Autodesk Maya" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
