0x06. Python - Classes and Objects
- My first square
Write an empty class Square that defines a square:
You are not allowed to import any module
- Square with size
Write a class Square that defines a square by: (based on 0-square.py)
Private instance attribute: size Instantiation with size (no type/value verification) You are not allowed to import any module Why?
Why size is private attribute?
The size of a square is crucial for a square, many things depend of it (area computation, etc.), so you, as class builder, must control the type and value of this attribute. One way to have the control is to keep it privately. You will see in next tasks how to get, update and validate the size value.
- Size validation
Write a class Square that defines a square by: (based on 1-square.py)
Private instance attribute: size Instantiation with optional size: def init(self, size=0): size must be an integer, otherwise raise a TypeError exception with the message size must be an integer if size is less than 0, raise a ValueError exception with the message size must be >= 0 You are not allowed to import any module
- Area of a square
Write a class Square that defines a square by: (based on 2-square.py)
Private instance attribute: size Instantiation with optional size: def init(self, size=0): size must be an integer, otherwise raise a TypeError exception with the message size must be an integer if size is less than 0, raise a ValueError exception with the message size must be >= 0 Public instance method: def area(self): that returns the current square area You are not allowed to import any module
- Access and update private attribute
Write a class Square that defines a square by: (based on 3-square.py)
Private instance attribute: size: property def size(self): to retrieve it property setter def size(self, value): to set it: size must be an integer, otherwise raise a TypeError exception with the message size must be an integer if size is less than 0, raise a ValueError exception with the message size must be >= 0 Instantiation with optional size: def init(self, size=0): Public instance method: def area(self): that returns the current square area You are not allowed to import any module Why?
Why a getter and setter?
Reminder: size is a private attribute. We did that to make sure we control the type and value. Getter and setter methods are not 100% Python, but more OOP. With them, you will be able to validate the assignment of a private attribute and also define how getting the attribute value will be available from outside - by copy? by assignment? etc. Also, adding type/value validation in the setter will centralize the logic, since you will do it in only one place.
- Printing a square
Write a class Square that defines a square by: (based on 4-square.py)
Private instance attribute: size: property def size(self): to retrieve it property setter def size(self, value): to set it: size must be an integer, otherwise raise a TypeError exception with the message size must be an integer if size is less than 0, raise a ValueError exception with the message size must be >= 0 Instantiation with optional size: def init(self, size=0): Public instance method: def area(self): that returns the current square area Public instance method: def my_print(self): that prints in stdout the square with the character #: if size is equal to 0, print an empty line You are not allowed to import any module
- Coordinates of a square
Write a class Square that defines a square by: (based on 5-square.py)
Private instance attribute: size: property def size(self): to retrieve it property setter def size(self, value): to set it: size must be an integer, otherwise raise a TypeError exception with the message size must be an integer if size is less than 0, raise a ValueError exception with the message size must be >= 0 Private instance attribute: position: property def position(self): to retrieve it property setter def position(self, value): to set it: position must be a tuple of 2 positive integers, otherwise raise a TypeError exception with the message position must be a tuple of 2 positive integers Instantiation with optional size and optional position: def init(self, size=0, position=(0, 0)): Public instance method: def area(self): that returns the current square area Public instance method: def my_print(self): that prints in stdout the square with the character #: if size is equal to 0, print an empty line position should be use by using space - Don’t fill lines by spaces when position[1] > 0 You are not allowed to import any module