Python object's attribute

Question

I have a python question about object's attribute. Code:

>>> class A(object):
...   dict = {}
...   def stuff(self, name):
...     self.dict[name] = 'toto'
... 
>>> a = A()
>>> print a.dict
{}
>>> a.stuff('un')
>>> print a.dict
{'un': 'toto'}
>>> b = A()
>>> print b.dict
{'un': 'toto'}

I'm a PHP devlopper and in PHP rint b.dict will be {}. Why python share this attribute between a and b ? What is the way to define class attribute who will be new on new instantiation?

Martijn Pieters · Accepted Answer · 2013-11-07 12:35:30Z

3

You created a class attribute, not an instance attribute. The dictionary is mutable, you can alter it from instances or on the class directly, but class attributes are by definition shared among all instances.

Create a new empty dictionary in the __init__ method instead:

class A(object):
    def __init__(self):
        self.dict = {}

    def stuff(self, name):
        self.dict[name] = 'toto'

answered Nov 7, 2013 at 12:35

Martijn Pieters

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