CODEWITHSUNDEEP
python
ManInBlue
ManInBlue

Reputation: 15

How to return an instance's attribute by default

In my code, I have a data store with multiple variables set to instances of a class similar to that below. (The reason is that this Interval class has lots of operator overriding functions).

class Interval(object):

    def __init__(self, value):
         self.value = value


data_store.a = Interval(1)

I want any references to data_store.a to return self.value rather than the Interval instance. Is this possible?

Upvotes: 0

Views: 45

Answers (2)

jonrsharpe
jonrsharpe

Reputation: 122153

As an alternative to Malik's answer, you could make a a @property, the Pythonic equivalent of get and set for managing access to internal attributes:

class DataStore(object):

    def __init__(self):
        self.a = Interval(1)

    @property
    def a(self):
        return self._a.value

    @a.setter
    def a(self, value):
        self._a = value

Here _a is a private-by-convention attribute that stores the Interval instance. This works as you want it:

>>> store = DataStore()
>>> store.a
1

Upvotes: 1

Malik Brahimi
Malik Brahimi

Reputation: 16721

You need to extend your data store whose attribute is an interval object:

class DataStore(object):

    def __init__(self):
        self.a = Interval(1)

    def __getattribute__(self, attr):

        if attr == 'a':
            return object.__getattribute__(self, 'a').value

        if attr != 'a':
            return object.__getattribute__(self, attr)

Upvotes: 0

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