Getting AttributeError after invoking class function in Python

Question

Very simple class(source below) written in Python.

After constructing obj1 = myClass(12) and calling class function obj1.printInfo(), I am getting an error - AttributeError: type object 'myClass' has no attribute 'arg1' What might be the source of the problem ??

class myClass(object):

    def __init__(self, arg1, arg2 = 0):
        self.arg1 = arg1
        self.arg2 = arg2

    def printInfo (self):
        print myClass.arg1, myClass.arg2


obj1 = myClass(12)
obj1.printInfo()

Thanks !

Mike Axiak · Accepted Answer · 2010-12-07 23:07:36Z

3

You want to use replace the body of printInfo(self) with:

def printInfo(self):
    print self.arg1, self.arg2

The use of self here is not to specify the scope, as it is sometimes used in Java (MyClass.this) or in PHP. In this function, self is actcually the object that contains arg1 and arg2. Python is very explicit in this manner. In your previous method, you assigned arg1 and arg2 for self, so you should expect to get arg1 and arg2 back off of self.

With regard to your second question, if you want a "class" function (i.e. a static method), then you still need a reference to your obj1 to access its properties. For example:

class MyClass(object):

    def __init__(self, arg1, arg2 = 0):
        self.arg1 = arg1
        self.arg2 = arg2

    @staticmethod
    def printInfo(obj):
        print obj.arg1, obj.arg2


obj1 = MyClass(12)
MyClass.printInfo(obj1)

Also be sure to read PEP8 when you get a chance :)

edited Dec 7, 2010 at 23:07

answered Dec 7, 2010 at 2:43

Mike Axiak

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2 Comments

newprint Over a year ago

Thanks for an Answer. I will extend this question a little, what if I have some non-class function f1() that will be called by printInfo() and f1() would use obj1 arguments. Would this be possible at all ? Thanks !

Mike Axiak Over a year ago

Edited answer to reflect your comment.

John Kugelman · Accepted Answer · 2010-12-07 02:43:30Z

1

Brain fart, eh? Switch myClass.arg1 to self.arg1:

def printInfo (self):
    print self.arg1, self.arg2

answered Dec 7, 2010 at 2:43

John Kugelman

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Comments

Svante · Accepted Answer · 2011-09-16 09:44:27Z

0

You can do it like this:

def f1(arg1, arg2):
    print arg1, arg2

class myClass(object):
    def __init__(self, arg1, arg2 = 0):
        self.arg1 = arg1
        self.arg2 = arg2
    def printInfo (self):
        f1(self.arg1, self.arg2)

obj1 = myClass(12)
obj1.printInfo()

edited Sep 16, 2011 at 9:44

Svante

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answered Dec 7, 2010 at 12:27

Dharmesh Patel

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