Day3

# Exceptions

# try:

#     num = int(input("input a number: "))

# except ValueError as ex:

#     print(ex)

# else:

#     print("continue")

# note: the type of ex is ValueError

# handling different type of exceptions

# there are some other types of exceptions like ZeroDivisionError, ValueError, etc.

# how to control different errors in one try blcok

# try:

#     file1 = open("day3.py")

#     age = int(input("Age: "))

#     tmp = 10/age

#     file1.close()

# except (ValueError, ZeroDivisionError) as ex:

#     print(ex)

# else:

#     print("continue")

# use finally clause to execute the last operation

# this piece of code above will be executed at the end of try block

# use "with" statement to make the code more readable and cleaner

# the with statement below is to automatically release external res

# try:

#     with open("day3.py") as file1, open("day2.py") as file2:

#         print("file open")

# except NameError as ex:

#     print(ex)

# Class

# class attributes and instance attributes

# class attributes belong to all the instance of the class, they differ from instance attributes in that they are

# owned by one specific instance of the class and are not share between instances

# class methods and instance methods

# here method, draw, above is an instance method, we need an instance to call it, by contrast, we do not need an instance to call

# class Point:

#     default_color = "red"

#     def __init__(self, x, y):

#         self.x = x

#         self.y = y

#     @classmethod

#     def zero(cls):

#         return cls(0, 0)

#     def draw(self):

#         print(f"({self.x},{self.y})")

# point = Point(1, 2)

# point = Point.zero()

# point.draw()

# Magic methods

# magic methods usually used for overloading the operators

# new words: under score '_'

class Point:

    def __init__(self, x, y):

        self.x = x

        self.y = y

    def __str__(self):

        return f"{self.x},{self.y}"

    def __eq__(self, other):

        return self.x == other.x and self.y == other.y

point = Point(1, 2)

print(str(point))

point1 = Point(1, 2)

print(point == point1)

# here we use "str()" to call magic method