About classes and OOP in Python

[Sion Arrowsmith]

fyhuang <fyhuang at gmail.com> wrote:
> [ ... ] no such thing as a private variable. Any
>part of the code is allowed access to any variable in any class, and
>even non-existant variables can be accessed: they are simply created.

You're confusing two issues: encapsulation and dynamic name binding.
You might also want to check out the difference between read and
write access to non-existant variables.

>I'm wondering what the philosophy behind this is,

"We are all consenting adults." And probably experience of data
encapsulation being more of a hinderence than a benefit.

> and if this
>behaviour is going to change in any future release of Python.

I damn well hope not.

And if you want to control those writes, try this for a base class:

class restrict_set:
    def __init__(self, allowed_names):
        self._allowed_names = set(allowed_names)
    def __setattr__(self, name, value):
        if not name.startswith('_') and name not in self._allowed_names:
            getattr(self, name)
        self.__dict__[name] = value

(Someone else can do the new style class and the metaclass versions.)

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