private-attribute 2.4.4

Private attribute decorator for Python classes

Private Attribute

Introduction

This package provide a way to create the private attribute like "C++" does.

Usage

This is a simple usage about the module:

from private_attribute import PrivateAttrBase

class MyClass(PrivateAttrBase):
    __private_attrs__ = ['a', 'b', 'c']
    def __init__(self):
        self.a = 1
        self.b = 2
        self.c = 3

    def public_way(self):
        print(self.a, self.b, self.c)

obj = MyClass()
obj.public_way()  # (1, 2, 3)

print(hasattr(obj, 'a'))  # False
print(hasattr(obj, 'b'))  # False
print(hasattr(obj, 'c'))  # False

All of the attributes in __private_attrs__ will be hidden from the outside world, and stored by another name.

You can use your function to generate the name. It needs the id of the obj and the name of the attribute:

def my_generate_func(obj_id, attr_name):
    return some_string

class MyClass(PrivateAttrBase, private_func=my_generate_func):
    __private_attrs__ = ['a', 'b', 'c']
    def __init__(self):
        self.a = 1
        self.b = 2
        self.c = 3

    def public_way(self):
        print(self.a, self.b, self.c)

obj = MyClass()
obj.public_way()  # (1, 2, 3)

If the method will be decorated, the property, classmethod and staticmethod will be supported. For the other, you can use the PrivateWrapProxy to wrap the function:

from private_attribute import PrivateAttrBase, PrivateWrapProxy

class MyClass(PrivateAttrBase):
    __private_attrs__ = ['a', 'b', 'c']
    @PrivateWrapProxy(decorator1())
    @PrivateWrapProxy(decorator2())
    def method1(self):
        ...

    @method1.attr_name
    @PrivateWrapProxy(lambda _: _) # use empty function to wrap
    def method1(self):
        ...

    @PrivateWrapProxy(decorator3())
    def method2(self):
        ...

    @method2.attr_name
    @PrivateWrapProxy(lambda _: _)
    def method2(self):
        ...

Notes

• All of the private attributes class must contain the __private_attrs__ attribute.
• The __private_attrs__ attribute must be a sequence of strings.
• You cannot define the name which in __slots__ to __private_attrs__.
• When you define __slots__ and __private_attrs__ in one class, the attributes in __private_attrs__ can also be defined in the methods, even though they are not in __slots__.
• All of the object that is the instance of the class "PrivateAttrBase" or its subclass are default to be unable to be pickled.
• Finally the attributes' names in __private_attrs__ will be change to a tuple with two hash.

License

MIT