Trouble with class inheritance - Python

Question

I'm fairly new to python and was having trouble with an inheritance classes. This is for an online introduction to computer programming class and I do not have the resources to figure out where I went wrong with my code. Here is the code:

class Employee:
    def __init__(self, employeeName, employeeShift):
        self.__name = employeeName
        self.__number = employeeShift

    def set_name(self, nam):
        self.__name = nam

    def set__number(self, num):
        self.__number = num

    # Accessor methods
    def get_name(self):
        return self.__name

    def get_number(self):
        return self.__number

# ProductionWorker class that inherited the Employee class
class ProductionWorker(Employee):
    def __init__(self, shift, payRate):
        self.__shift_number = shift
        self.__pay_rate = payRate

    def set_shift_number(self, shift):
        self.__shift_number = shift

    def set_pay_rate(self, pay):
        self.__pay_rate = pay

    # Accessor methods
    def get_shift(self):
        return self.__shift

    def get_shift(self):
        if self.__shift_number = '1':
            s = 'Day shift'
        else self.__shift_number = '2':
            s = 'Night shift'
        return s 

    def get_pay(self):
        return self.__pay

    def get_pay(self):
        if self.__pay_rate <= 5:
            p = 7.50
        elif self.__pay_rate > 5 and self.__pay_rate <= 15:
            p = 13.50
        else self.__pay_rate >= 20:
            p = 20
        return p

# main module
def main():
    # Prompts the user for employee name, shift and pay rate
    employeeName = raw_input("Please enter the employee name: ")
    print "Please enter which shift the employee works."
    employeeShift = input("1 for day shift, 2 for night shift: ")
    payRate = input("How long has the employee worked here? ")

    # Creates object of ProductionWorker
    worker = ProductionWorker(employeeName, employeeShift, payRate)

    # Displays information
    print "Employee name:", worker.get_name()
    print "Employee shift:", worker.get_shift()
    print "Employee pay rate:", worker.get_pay_rate()

# calls main module
main()

It tells me that there is a syntax error in the ProductionWorker class, under the def get_shift() where I have the self.__shift_number = '1'. I followed my professor's example, so I don't really understand this error.

Answer 1

You should be using '==' instead of '=' in the get_shift function.

• = is the assignment operator

• == is the comparison operator

Corrected Code:

---

def get_shift(self):
    if self.__shift_number == '1':
        s = 'Day shift'
    elif self.__shift_number == '2':
        s = 'Night shift'
    return s 

---

Answer 2

Python uses == for comparison tests:

if self.__shift_number == '1':

= if for variable assignment.

---

Edit:

You actually have a few more problems. Before I get into them, here is a fixed version of your script:

class Employee:
    def __init__(self, employeeName, employeeShift):
        self.name = employeeName
        self.number = employeeShift

    def set_name(self, nam):
        self.name = nam

    def setnumber(self, num):
        self.number = num

    # Accessor methods
    def get_name(self):
        return self.name

    def get_number(self):
        return self.number

# ProductionWorker class that inherited the Employee class
class ProductionWorker(Employee):
    ##############################################
    def __init__(self, name, shift, payRate):
        self.name = name
    ##############################################
        self.shift_number = shift
        self.pay_rate = payRate

    def set_shift_number(self, shift):
        self.shift_number = shift

    def set_pay_rate(self, pay):
        self.pay_rate = pay

    # Accessor methods
    def get_shift(self):
       if self.shift_number == 1:
            s = 'Day shift'
       ###################################
       elif self.shift_number == 2:
       ###################################
            s = 'Night shift'
       return s 

    def get_pay(self):
        if self.pay_rate <= 5:
            p = 7.50
        elif self.pay_rate > 5 and self.pay_rate <= 15:
            p = 13.50
        ###################################
        elif self.pay_rate >= 20:
        ###################################
            p = 20
        return p

# main module
def main():
    # Prompts the user for employee name, shift and pay rate
    employeeName = raw_input("Please enter the employee name: ")
    print "Please enter which shift the employee works."
    employeeShift = input("1 for day shift, 2 for night shift: ")
    payRate = input("How long has the employee worked here? ")

    # Creates object of ProductionWorker
    worker = ProductionWorker(employeeName, employeeShift, payRate)

    # Displays information
    print "Employee name:", worker.get_name()
    print "Employee shift:", worker.get_shift()
    print "Employee pay rate:", worker.get_pay()

# calls main module
main()

Now here is what I did:

1. Replaced all of your else's with elif's (since else does not support a condition).

2. Except the ones in __init__, I removed every double underscore. This is because double underscores, when used like that, have a special meaning in Python.

3. Added a name parameter to ProductionWorker.__init__ (since you pass a name in on this line: worker = ProductionWorker(employeeName, employeeShift, payRate)).

4. Just below the declaration of ProductionWorker.__init__, I added this line to give ProductionWorker a name attribute: self.name = name.

Answer 3

In addition to the bug pointed out by @iCodez, you haven't defined what self.__shift is, so get_shift() will raise an error when you call it.

You also haven't defined what self.__pay is, so get_pay() will throw a NameError.

I assume you meant those methods to return self.__shift_number and self.pay_rate, respectively.

Haha, actually now that I look closer, you double-define those methods, so you immediately overwrite your buggy code with more-correct code. I suggest you delete your buggy code.