Class method.. Print the monthly interest amount. Python

Question

I am making a program that uses the class Account to print the monthly interest amount of accountA, among other things. I am having problems with getting the getMonthlyInterestRate() and getMonthlyInterest definitions to work out. Here is the program thus far:

Account.py

class Account:
    def __init__(self,id=0,balance=100.0,annualInterestRate=0.0):
        self.__id=id
        self.__balance=balance
        self.__annualInterestRate=annualInterestRate
    def getId(self):
        return self.__id
    def getBalance(self):
        return self.__balance
    def getAnnualInterest(self):
        return self.__annualInterestRate
    def setId(self,newid):
        self.__id=newid
    def setBalance(self,newbalance):
        self.__balance=newbalance
    def setAnnualInterestRate(self,newannualInterestRate):
        self.__annualInterestRate=newannualInterestRate
    def getMonthlyInterestRate(self,getAnnualInterest):
        return(getAnnualInterest(self)/12)
    def getMonthlyInterest(self,getBalance,getMonthly):
        return(getBalance(self)*getMonthlyInterestRate(self))

    def withdraw(self,amount):
        if(amount<=self.__balance):
            self.__balance=self.__balance-amount
    def deposit(self,amount):
        self.__balance=self.__balance+amount
    def __str__(self):
        return "Account ID : "+str(self.__id)+" Account Balance : "+str(self.__balance)+" Annual Interest Rate : "+str(self.__annualInterestRate)

from Account import Account

def main():
    accountA=Account(0,100,0)
    accountA.setId(1234)
    accountA.setBalance(20500)
    accountA.setAnnualInterestRate(0.375)
    print(accountA.__str__())
    accountA.withdraw(500)
    accountA.deposit(1500)
    print(accountA.__str__())
    print(accountA.getMonthlyInterest(accountA.getBalance(),accountA.getAnnualInterest())) 
main()

I cannot figure out how to make the getMonthlyInterestRate() and getMonthlyInterest() defintions to work out to be able to put out the right output, which is:

Account ID :  1234 Account Balance :  20500 Annual Interest Rate :  0.375

Account ID :  1234 Account Balance :  21500 Annual Interest Rate :  0.375

Monthly Interest Amount :  671.875

mine always comes out with the error statement:

Account ID : 1234 Account Balance : 20500 Annual Interest Rate : 0.375
Account ID : 1234 Account Balance : 21500 Annual Interest Rate : 0.375
Traceback (most recent call last):
  File "C:Program Files (x86)Wing IDE 101 4.1srcdebugtserver_sandbox.py", line 13, in <module>
  File "C:Program Files (x86)Wing IDE 101 4.1srcdebugtserver_sandbox.py", line 12, in main
  File "C:UsersMeaganDocumentsUniversity2nd YearCmput 174Account.py", line 21, in getMonthlyInterest
    return(getBalance(self)*getMonthlyInterestRate(self))
builtins.TypeError: 'int' object is not callable

this is what i should make:

a method named getMonthlyInterestRate() that returns the monthly interest rate.
a method named getMonthlyInterest() that return the monthly interest amount. The monthly interest amount can be calculated by using balance * monthly interest rate. The monthly interest rate can be computed by dividing the annual interest rate by 12.

everything else in the program is correct except for those two definitions and the last print statement. Any help would be appreciated. Thanks.

Asked By: Sofia June

||

Source

Answer 1

You should call methods on self, not by passing the functions around:

def getMonthlyInterest(self):
    return self.getBalance() * self.getMonthlyInterestRate()

and call it with:

print(accountA.getMonthlyInterest())

This goes for getMonthlyInterestRate as well:

def getMonthlyInterestRate(self):
    return self.getAnnualInterest() / 12

You use a lot of getters and setters; there is no need for these in Python; you don’t need to make the attributes private, just access them directly instead:

class Account:
    def __init__(self, id=0, balance=100.0, annualInterestRate=0.0):
        self.id = id
        self.balance = balance
        self.annualInterestRate = annualInterestRate

    def getMonthlyInterestRate(self):
        return self.annualInterestRate / 12

    def getMonthlyInterest(self):
        return self.balance * self.getMonthlyInterestRate()

    def withdraw(self, amount):
        if amount <= self.balance:
            self.balance -= amount

    def deposit(self, amount):
        self.balance += amount

    def __str__(self):
        return "Account ID : {0.id} Account Ballance : {0.balance} Annual Interest Rate : {0.annualInterestRate}".format(self)

then run:

def main():
    accountA = Account(0,100,0)
    accountA.id = 1234
    accountA.balance = 20500
    accountA.annualInterestRate = 0.375
    print(accountA)
    accountA.withdraw(500)
    accountA.deposit(1500)
    print(accountA)
    print(accountA.getMonthlyInterest())

Result:

Account ID : 1234 Account Ballance : 20500 Annual Interest Rate : 0.375
Account ID : 1234 Account Ballance : 21500 Annual Interest Rate : 0.375
671.875

Answered By: Martijn Pieters

Answer 2

You define

def getMonthlyInterestRate(self,getAnnualInterest):
    return(getAnnualInterest(self)/12)
def getMonthlyInterest(self,getBalance,getMonthly):
    return(getBalance(self)*getMonthlyInterestRate(self))

and use them as

print(accountA.getMonthlyInterest(accountA.getBalance(),accountA.getAnnualInterest()))

in other words, you call them with the return values of the said functions, not with the functions themselves. Inside these functions, you try to call them again. As you didn’t pass functions, but values, this “calling again” fails.

If you fix this bug, you (probably) make your program work, but youget a program written in very bad style.

To improve that, follow Martijn Pieters’s hint.

(This answer should probably have been a comment, but these cannot be formatted nicely.)

Answered By: glglgl

Class method.. Print the monthly interest amount. Python

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