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 !

Answer 1

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 :)

• newprint: 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: Edited answer to reflect your comment.

Answer 2

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

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

Answer 3

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()