• dneaves@lemmy.world
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    5 months ago

    You can feign immutablility on class attributes by playing with __setattr__. I don’t remember the exact way to do it, but its roughly like this:

    class YourClass:
        def __setattr__(self, name, value):
            if not hasattr(self, name):
                super().__setattr__(name, value)
           else:
                # handle as you wish if the
                # attr/value already exists.
                # pass, raise, whatever
    

    I say “feign immutability” because there are still cases in which an attr value can change, such as:

    • the underlying attribute contains a list and appending to the list
    • the underlying attribute is a class and modifying the class’s attributes
    • pretty much anything that does “in place” changes, because so much of python is referential and has side effects.