CODEWITHSUNDEEP
pythonobjectinheritance
Ashutosh
Ashutosh

Reputation: 4675

Python asking for two arguments when one needs to be passed

I'm new to python and was working on this code:

class Shape:
    def __init__(self, shape):
        self.shape = shape

    def shapeName(self):
        print(self.shape)

class Rectangle(Shape):                         # Rectangle class inherits Shape

    count = 0                                   # static variable

    def __init__(self, name):
        Shape.__init__(self.name)
        print('In Rectangle')
        Rectangle.count = Rectangle.count + 1


rec1 = Rectangle('Rectangle')
rec2 = Rectangle('Rectangle')

rec1.shapeName()
rec2.shapeName()

print( Rectangle.count )

I'm getting the following error:

C:\Python32\python.exe C:/Users/ashutosh/PycharmProjects/Test/InheritanceTest.py

Traceback (most recent call last):

File "C:/Users/ashutosh/PycharmProjects/Test/InheritanceTest.py", line 17, in <module>

rec = Rectangle('Rectangle')

File "C:/Users/ashutosh/PycharmProjects/Test/InheritanceTest.py", line 13, in __init__

Shape.__init__(name)

TypeError: __init__() takes exactly 2 arguments (1 given)

Process finished with exit code 1

The first argument to constructor is the current object and second is the name of the shape. Then why it is saying that I have to pass 2 arguments?

Upvotes: 1

Views: 162

Answers (2)

keyser
keyser

Reputation: 19189

Shape is a class, not an object, so when you call Shape.__init__ there's no self variable. In other words, there is no instance of Shape to call init on. The instance you want is the subclass instance of Shape that you have, i.e. self (the Rectangle). You could simply pass self, like this:

Shape.__init__(self, name)

or make use of the super keyword:

super(Rectangle, self).__init__(name)

The super keyword allows you to implicitly refer to your superclass, without using the name.

In Python 3.0 you can simply write super().__init__(name) without even the child reference.

Upvotes: 4

Sherlock
Sherlock

Reputation: 5627

You have to pass self explicitly to Shape.__init__.

So your rectangle class should look like this:

class Rectangle(Shape):                         # Rectangle class inherits Shape

    count = 0

    def __init__(self, name):
        Shape.__init__(self, name)
        print('In Rectangle')

Upvotes: 4

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