Due by 11:59pm on Wednesday, October 23

Instructions

Download hw07.zip. Inside the archive, you will find a file called hw07.py, along with a copy of the ok autograder.

Submission: When you are done, submit the assignment by uploading all code files you've edited to Gradescope. You may submit more than once before the deadline; only the final submission will be scored. Check that you have successfully submitted your code on Gradescope. See Lab 0 for more instructions on submitting assignments.

Using Ok: If you have any questions about using Ok, please refer to this guide.

Grading: Homework is graded based on correctness. Each incorrect problem will decrease the total score by one point. This homework is out of 2 points.

Required Questions

Midsemester Survey

Q1: Mid-Semester Feedback

As part of this assignment, fill out the Mid-Semester Feedback form.

Once you finish the survey, you will be presented with a passphrase. Put this passphrase, as a string, on the line that says passphrase = 'REPLACE_THIS_WITH_PASSPHRASE' in the Python file for this assignment. E.g. if the passphrase is abc, then the line should be passphrase = 'abc'.

Use Ok to test your code:

python3 ok -q midsem_survey
Copy
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Object-Oriented Programming

Q2: Vending Machine

In this question you'll create a vending machine that sells a single product and provides change when needed.

Implement the VendingMachine class, which models a vending machine for one specific product. The methods of a VendingMachine object return strings to describe the machine’s status and operations. Ensure that your output matches exactly with the strings provided in the doctests, including punctuation and spacing.

You may find Python's formatted string literals, or f-strings useful. A quick example:

>>> feeling = 'love'
>>> course = '61A!'
>>> combined_string = f'I {feeling} {course}'
>>> combined_string
'I love 61A!'

class VendingMachine:
    """A vending machine that vends some product for some price.

    >>> v = VendingMachine('candy', 10)
    >>> v.vend()
    'Nothing left to vend. Please restock.'
    >>> v.add_funds(15)
    'Nothing left to vend. Please restock. Here is your $15.'
    >>> v.restock(2)
    'Current candy stock: 2'
    >>> v.vend()
    'Please add $10 more funds.'
    >>> v.add_funds(7)
    'Current balance: $7'
    >>> v.vend()
    'Please add $3 more funds.'
    >>> v.add_funds(5)
    'Current balance: $12'
    >>> v.vend()
    'Here is your candy and $2 change.'
    >>> v.add_funds(10)
    'Current balance: $10'
    >>> v.vend()
    'Here is your candy.'
    >>> v.add_funds(15)
    'Nothing left to vend. Please restock. Here is your $15.'

    >>> w = VendingMachine('soda', 2)
    >>> w.restock(3)
    'Current soda stock: 3'
    >>> w.restock(3)
    'Current soda stock: 6'
    >>> w.add_funds(2)
    'Current balance: $2'
    >>> w.vend()
    'Here is your soda.'
    """
    def __init__(self, product, price):
        """Set the product and its price, as well as other instance attributes."""
        "*** YOUR CODE HERE ***"

    def restock(self, n):
        """Add n to the stock and return a message about the updated stock level.

        E.g., Current candy stock: 3
        """
        "*** YOUR CODE HERE ***"

    def add_funds(self, n):
        """If the machine is out of stock, return a message informing the user to restock
        (and return their n dollars).

        E.g., Nothing left to vend. Please restock. Here is your $4.

        Otherwise, add n to the balance and return a message about the updated balance.

        E.g., Current balance: $4
        """
        "*** YOUR CODE HERE ***"

    def vend(self):
        """Dispense the product if there is sufficient stock and funds and
        return a message. Update the stock and balance accordingly.

        E.g., Here is your candy and $2 change.

        If not, return a message suggesting how to correct the problem.

        E.g., Nothing left to vend. Please restock.
              Please add $3 more funds.
        """
        "*** YOUR CODE HERE ***"

Use Ok to test your code:

python3 ok -q VendingMachine
Copy
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Check Your Score Locally

You can locally check your score on each question of this assignment by running

python3 ok --score

This does NOT submit the assignment! When you are satisfied with your score, submit the assignment to Gradescope to receive credit for it.

Submit Assignment

Submit this assignment by uploading any files you've edited to the appropriate Gradescope assignment. Lab 00 has detailed instructions.

Exam Practice

These questions have no submission component; feel free to attempt them if you'd like some practice!

Object-Oriented Programming

1. Spring 2022 MT2 Q8: CS61A Presents The Game of Hoop.
2. Fall 2020 MT2 Q3: Sparse Lists
3. Fall 2019 MT2 Q7: Version 2.0