Error in writing a class.

Question

I am running through a tutorial online at http://www.sthurlow.com/python/lesson08/ and I believe I understand how classes work in python, at least to some degree but when I run this code:

class Shape:
    def __init__(self,x,y):
        self.x = x
        self.y = y
    description = "This shape has not been described yet"
    author = "Nobody has claimed to make this shape yet"
    def area(self):
        return self.x * self.y
    def perimeter(self):
        return 2 * self.x + 2 * self.y
    def describe(self,text):
        self.description = text
    def authorName(self,text):
        self.author = text
    def scaleSize(self,scale):
        self.x = self.x * scale
    self.y = self.y * scale

I get this error:

Traceback (most recent call last):
  File "Y:/python/Shape.py", line 1, in -toplevel-
    class Shape:
  File "Y:/python/Shape.py", line 17, in Shape
    self.y = self.y * scale
NameError: name 'self' is not defined

Any Help would be great

Thanks

Richard

Answer 1

You need to indent the last line.

def scaleSize(self,scale): 
    self.x = self.x * scale 
self.y = self.y * scale 

Should be

def scaleSize(self,scale): 
    self.x = self.x * scale 
    self.y = self.y * scale 

Answer 2

The indicated line has the wrong indent level, so it's not in the scaleSize() method.

Answer 3

The last part of your code is wrong,

def scaleSize(self,scale):
    self.x = self.x * scale
self.y = self.y * scale

Notice the indentation, which is important in Python. By what you have now, means self.y = self.y * scale is not inside the scaleSize method and the keyword self is undefined for your Shape class.

What you need to do is properly indent,

def scaleSize(self,scale):
    self.x = self.x * scale
    self.y = self.y * scale

Answer 4

You need to align line 17 with line 16

You have:

def scaleSize(self,scale):
    self.x = self.x * scale
self.y = self.y * scale

Must be:

def scaleSize(self,scale):
    self.x = self.x * scale
    self.y = self.y * scale

That's how python knows they belong to the same method.