I don't know why I am getting the error: NameError: name 'changeRate' is not defined

Question

This is my code:

w1 = ch8.Worker("Joe", 15)
print(w1.pay(35))  # Not implemented

w2 = ch8.SalariedWorked("Sue", 14.50)
print(w2.pay())  # 580.0
print(w2.pay(60))  # 580.0

w3 = ch8.HourlyWorker("Dana", 20)
print(w3.pay(25))  # 500
w3 = changeRate(35)
print(w3.pay(35))  # 875

And this is the classes Worker, SalarieWorked and HourlyWorker that I implemented in the file ch8.py:

class Worker:
    def __init__(self, worker_name="Unknown", hourly_pay_rate=0.0):
        self.worker_name = str(worker_name)
        self.hourly_pay_rate = float(hourly_pay_rate)

    def changeRate(self, new_pay_rate):
        self.new_pay_rate = float(new_pay_rate)
        self.hourly_pay_rate = self.new_pay_rate

    def pay(self, number_of_hours):
        self.number_of_hours = number_of_hours
        return "Not implemented"


class HourlyWorker(Worker):
    def pay(self, number_of_hours):
        self.number_of_hours = int(number_of_hours)
        if self.number_of_hours > 40:
            return (
                40 * self.hourly_pay_rate
                + (self.number_of_hours - 40) * self.hourly_pay_rate * 2
            )
        return self.number_of_hours * self.hourly_pay_rate


class SalariedWorked(Worker):
    def pay(self, number_of_hours=40):
        self.number_of_hours = int(number_of_hours)
        return 40 * self.hourly_pay_rate

This is what I get when I execute the code:

Not implemented
580.0
580.0
500.0
Traceback (most recent call last):
File "C:\\Users\\carol\\PycharmProjects\\ProblemasPraticos\\book_Intro_Computing_Using_Python\\Chapter 8\\8_Exercises.py", line 137, in
w3 = changeRate(35)
NameError: name 'changeRate' is not defined

Someone could help me to understand why this error?

Thanks!

Answer 1

you write w3.pay(25)

w3 = changeRate(35)

why not w3.changeRate(35)

Answer 2

You are overriding the function.

When you call w3 = ch8.HourlyWorker("Dana", 20) you are creating an object w3 of type HourlyWorker.

Then you are assigning a function to the class object when you write w3 = changeRate(35)

This is not permitted.

Try doing just w3.changeRate(35) instead of **w3 = changeRate(35)**

Answer 3

changeRate is a method of Worker class, so to use it, you need to call it from class instanse

Exsample:

w3.changeRate(35)

Answer 4

changeRate() is a method of the class Worker . So, you have to call it through an instance of the class. The class HourlyWorker inherits from the class Worker . So the method changeRate() is available in the class HourlyWorker .

To achieve your goal, replace the line w3 = changeRate(35) by this line: w3.changeRate(35)