Steve Jobless wrote: > Hi, > > I just started learning Python. I went through most of the tutorial at > python.org. But I noticed something weird. I'm not talking about the > __private hack. > > Let's say the class is defined as: > > class MyClass: > def __init__(self): > pass > def func(self): > return 123 > > But from the outside of the class my interpreter let me do: > > x = MyClass() > x.instance_var_not_defined_in_the_class = 456
Uh-huh. Could result from a typo. Found in testing. pychecker and/or pylint may help here. Use __slots__ if this bothers you. > > or even: > > x.func = 789 > > After "x.func = 789", the function is totally shot. So is the developer :-) > > Are these bugs or features? If they are features, don't they create > problems as the project gets larger? > Features. They don't *create* problems by themselves. If a project already has problems (like they hire idiots, and don't have appropriate review and testing), then yeah things can blow up because of some language features being mis-used -- this applies to any language. Further, there are lots more reasons why projects blow up, few of them related to a couple of features of the development language. Another way of looking at it: languages can't tell who's using them. If they constrain idiots, they also constrain non-idiots. Cheers, John -- http://mail.python.org/mailman/listinfo/python-list
