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pythonclass-attribute

Class attributes in Python

Is there any difference in the following two pieces of code? If not, is one preferred over the other? Why would we be allowed to create class attributes dynamically?

Snippet 1

class Test(object):
    def setClassAttribute(self):
        Test.classAttribute = "Class Attribute"

Test().setClassAttribute()

Snippet 2

class Test(object):
    classAttribute = "Class Attribute"

Test()
Solution

  • It's more natural to do it like #2, but notice that they do different things. With #2, the class always has the attribute. With #1, it won't have the attribute until you call setClassAttribute.

    You asked, "Why would we be allowed to create class attributes dynamically?" With Python, the question often is not "why would we be allowed to", but "why should we be prevented?" A class is an object like any other, it has attributes. Objects (generally) can get new attributes at any time. There's no reason to make a class be an exception to that rule.