Sum, Subtraction and Multiplication using Class and Object in Python

Sum, Subtraction and Multiplication using Class and Object in Python

I am just learning basic python. I i have committed any mistake please comment there and help me to learn more Thanks

Write code in caluclatorclass.py:

class Calculator:

    enterFirstNumber='Please enter first Number'

    enterSecondNumber='Please enter second Number'

    invalidValueString='Invalid value is passed to'

    def __init__(self):

        print('calculator __init_')

    def sum(self):

        try:

            number1=float(input(self.enterFirstNumber))

            number2=float(input(self.enterSecondNumber))

            print('Sum is:',number1+number2)

        except Exception  as e:

            print('{invalidValueString} sum.'.format(invalidValueString=invalidValueString))

    def subtraction(self):

        try:

            number1=float(input(self.enterFirstNumber))

            number2=float(input(self.enterSecondNumber))

            subtractionValue=number1-number2

            print('Subtraction is:{subtractionValue}'.format(subtractionValue=subtractionValue))

        except Exception  as e:

            print('{invalidValueString} subtraction.'.format(invalidValueString=invalidValueString))

    

    def multiplication(self):

        try:

            number1=float(input(self.enterFirstNumber))

            number2=float(input(self.enterSecondNumber))

            print('Multiplication is:{0}'.format(number1*number2))

        except Exception  as e:

            print('{invalidValueString} multiplication.'.format(invalidValueString=invalidValueString))

Write code in number-examples.py:

from calculatorclass import  Calculator

class Person:

    calculator=None

    def __init__(self,userName):

        #creats Calculator instance here.

        self.calculator=Calculator()

        #capitalize()/title() capitalizes the first Letter of string. 

        print('Welcome {userName}!'.format(userName=userName.capitalize())) 

        

    def whileloop(self):

        self.displayWhatUserCanInput()

        done=False

        while done==False:

            userinput=input('Enter 5 to exit and any other number to continue.')

            if  int(userinput)==5:

                print('Bye!')

                done=True

            else:

                self.displayWhatUserCanInput()

                done=False

    def displayWhatUserCanInput(self):

        print('''Please enter   1 for sum

               2 for subtraction

               3 for multiplication

                ''')

        try:

            options={

                1:self.calculator.sum,

                2:self.calculator.subtraction,

                3:self.calculator.multiplication

            }

            num=input('Please enter 1,2 or 3')

            func=options.get(int(num),'Invalid value found!')

            func()

        except Exception as ex:

            print (ex)

            print('Invalid value found')

class Welcome:

    def __init__(self):

        print('Welcome to the python demo calculator')

        userName=input('Please enter your name:  ')

        if not userName:

            print('You didn\'t enter your name')

        else:

            person=Person(userName)

            person.whileloop()

#Call welcome class here.

welcome=Welcome()

My observation:-

Here i found while creating classes and calling it.

1. If you have __init__() method in class to call it write abc=ClassName

2. If you have __init__(self) method in class  to call it write abc=ClassName()

3. If you have __init__(self,argument) method in class  to call it write abc=ClassName(argument_value) 

to execute it:-

write in terminal:-

py number-examples.py