ITECH1400 - Assignment 1 – Supermarket Self-Service Checkout
Due Date: 5pm, Friday of Week 7
This assignment will test your skills in designing and programming applications to specification and is worth 20% of your non-invigilated (type A) marks for this course. This is an INDIVIDUAL ASSIGNMENT – and while you may discuss it with your fellow students, you must not share designs or code or you will be in breach of the university plagiarism rules. This assignment should take you approximately 20 hours to complete.
You are tasked with creating a text-based program for simulating a supermarket self-service checkout using the Python 3 programming language.
The assignment is broken up into four main components:
1.) Design and model two classes: Product and CheckoutRegister,
2.) Create an activity chart which describes the behaviour of the checkout system,
3.) Create a computer program that allows a user to interactively check out a number of products, then provides an
opportunity to enter some virtual money to pay for the products and finally and prints out a receipt for the user (to the screen, not on paper), and finally
4.) Explain and integrate some code into your checkout program that places the products purchased into virtual shopping bags.
Your submission should consist of one Microsoft Word or LibreOffice document containing the first two parts of the assignment, and three Python scripts that implement the computer program (checkoutregister.py, product.py and main.py).
The main.py script runs the main logic of the program and will use instances of the CheckoutRegister and Product classes to simulate checking out of the supermarket.
You are provided with a Microsoft Word template to help you complete the first two parts of this assignment.
Towards the end of this document you will also be provided with the output of a simulated run of the completed computer program which may help you with this assignment.
Assignment Part 1 Details – Class Design
Think of a product that you can buy from a supermarket, like maybe a can of soup or an apple.
Start by listing all the properties of that object that you can think of – try to come up with at least ten general properties of a Product and write these down in your Assignment_Part_1_ YOUR_STUDENT_ID Microsoft Word document.
Next, use the process of abstraction to cut the number of properties back to only four ‘key’ properties – write these down in the next section of your Word document. Take a look at the week 2 lecture slides if you need a reminder on how to go about this.
Now, fill in the class diagram for your Product class in the Word document template provided. Your product class does not have to have any methods (i.e. functions) associated with it to perform any actions other than a constructor which takes and set the four key properties that you’ve identified.
Next we’ll move on to CheckoutRegister class – think about what information the checkout has to keep track of to allow you to successfully check out of the supermarket. There will only really be three key properties that the CheckoutRegister cares about, and the CheckoutRegister class should have the following four methods available:
1) A default constructor that takes no arguments and initialises a new object and its properties,
2) accept_payment(some_amount), 3) scan_item(some_product), and 4) print_receipt().
Fill in the class diagram for the CheckoutRegister class in the Word template, and that’s the first part completed!
Assignment Part 2 Details – Activity Flowchart
Using either the online website https://draw.io (preferred), or the applications Visio or Powerpoint – create an activity diagram of how the program should operate to successfully scan one or more products, accept payment, provide change and print a receipt for the user.
Make sure to use the correct symbols in your diagram for starting, processes, decisions/branches, and ending the process.
Although you should be familiar with how a self-checkout works, if not then you can always go to a local supermarket with a self-checkout and buy a packet of chewing gum or something – or take a look at a YouTube video of self-service checkout, such as this one: https://www.youtube.com/watch?v=hoyqVvHaL4s.
Don’t worry about loyalty/rewards cards to taking payment through debit or credit cards, our CheckoutRegister will only accept cash – although you can enter multiple denominations via multiple calls to the accept_money(some_amount) method. For example, calling accept_money(5.0) and then accept_money(2.0) will mean that the CheckoutRegister knows that you have entered a total of $7.00. Also note that you can start the entire checkout process off by simply scanning a product.
Once you have completed your activity flowchart, add it to your assignment template document.
Assignment Part 3 Details – Software Implementation
You are free to implement the software however you see fit, however the functionality of the software should be able to match the following output. Note that in the below run of the program I have ‘hard-coded’ a small number of Product instances so that products exist which can they can be checked out – in your code you should do the same.
Your program does not have to have the facility to add new products – just define a few and use them as demonstrated below. If the final option of (N)ext customer is chosen, the program should run again
Example Program Output
----- Welcome to FedUni checkout! -----
Please enter the barcode of your item: 123
Milk, 2 Litres - $2.0
Would you like to scan another product? (Y/N) y
Please enter the barcode of your item: 456
Bread - $3.5
Would you like to scan another product? (Y/N) y
Please enter the barcode of your item: 999 This product does not exist in our inventory.
Would you like to scan another product? (Y/N) n
Payment due: $5.5. Please enter an amount to pay: 5 Payment due: $0.5. Please enter an amount to pay: -3
We don't accept negative money!
Payment due: $0.5. Please enter an amount to pay: 2
----- Final Receipt -----
Milk, 2 Litres $2.0
Total amount due: $5.5
Amount received: $7.0
Change given: $1.5
Thank you for shopping at FedUni!
(N)ext customer, or (Q)uit? q
Part 4 – Code Explanation and Use
You are provided with the following two functions which you should
1. Analyse to determine what they do & provide documentation comments for, and
2. Incorporate into your final program solution.
Wherever there is a # followed by some underscores in the code below, you should write a short comment explaining what the below section of code is doing, and if there is space why it is doing it. Do part 1 of the above in the provided assignment 1 template document, rather than here!
# Function to: ___________________________ def get_float(prompt):
# ____________________________________ value = float(0.0)
# ____________________________________ while True: try:
# ____________________________________ value = float(input(prompt))
# ____________________________________ if value 0.0: print(-We don't accept negative money!-) continue
# ____________________________________ break
# ____________________________________ except ValueError:
print('Please enter a valid floating point value.')
# ____________________________________ return value
# Function to: ___________________________ def bag_products(product_list):
# ____________________________________ bag_list =  non_bagged_items =  MAX_BAG_WEIGHT = 5.0
# ____________________________________ for product in product_list:
# ____________________________________ if product.weight MAX_BAG_WEIGHT: product_list.remove(product) non_bagged_items.append(product)
# ____________________________________ current_bag_contents =  current_bag_weight = 0.0
# ____________________________________ while len(product_list) 0:
# ____________________________________ temp_product = product_list product_list.remove(temp_product)
# ____________________________________ if current_bag_weight + temp_product.weight = MAX_BAG_WEIGHT:
# ____________________________________ current_bag_contents.append(temp_product) current_bag_weight += temp_product.weight
# ____________________________________ else:
# ____________________________________ current_bag_contents = [temp_product] current_bag_weight = temp_product.weight
# ____________________________________ if (len(product_list) == 0):
# ____________________________________ for index, bag in enumerate(bag_list):
output = 'Bag ' + str(index + 1) + ' contains: '
# ____________________________________ for product in bag: output += product.name + ' ' print(output, '
# ____________________________________ if (len(non_bagged_items) 0): output = 'Non-bagged items: '
# ____________________________________ for item in non_bagged_items:
output += item + ' '
Submission and Marking Process
You must supply your program source code files and your document containing the first two section of the assignment as a single compressed archive called:
ITECH1400_Assignment_1_ YOUR-NAME _ YOUR-STUDENT-ID .zip
Obviously replace YOUR-NAME and YOUR-STUDENT-ID) with your own personal details! You may supply your word processed documentation in either Microsoft Word or LibreOffice/OpenOffice formats only – no proprietary Mac specific formats, please.
Assignments will be marked on the basis of fulfilment of the requirements and the quality of the work. In addition to the marking criteria, marks may be deducted for failure to comply with the assignment requirements, including (but not limited to):
• Incomplete implementation(s), and
• Incomplete submissions (e.g. missing files), and
• Poor spelling and grammar.
Submit your assignment (all program source files plus your word processed document) to the Assignment 1 Upload location on Moodle before the deadline of Friday of week 7 at 5pm.
The mark distribution for this assignment is explained on the next page – please look at it carefully and compare your submission to the marking guide.
Assignment 1 – FedUni Checkout
Student name: Student ID:
Part Assessment Criteria Weight Mark
1a Identification of properties of a typical supermarket Product. 10 * 0.5 = 5 marks
1b Application of abstraction to identify key properties of a typical supermarket Product as well as creation of a suitable Class Diagram. 4 marks
1c Identification of the key properties of a CheckoutRegister as well as creation of a suitable Class Diagram which uses those properties, plus the four method signatures provided. 4 marks
2 Creation of an activity flowchart which clearly indicates how the program should operate, using the correct symbols for elements such as start/end points, processes and decisions/branches 10 marks
3 Programming of the product checkout simulation so that it:
i) Creates a small number of Product instances that may be purchased, ii) Accepts simulated ‘scanning’ of a Product to identify it (including refusal to identify products which do not exist),
iii) Adds a scanned Product to the CheckoutRegister’s list of products being purchased,
iv) Allows the checkout of multiple products,
v) Accepts ‘virtual money’ to pay for those products (you must pay enough to cover the cost of the items checked out), and
vi) Prints a final receipt of the products purchased, along with the total cost, total paid and any change given. 5 + 5 + 5 +
5 + 5 + 5 = 30 marks.
i) ii) iiI)
4a Analysis and documentation via code comments of the two functions provided. (8 * 0.5) +
(16 * 0.5) =
4b Incorporation of the two functions provided into your main submission so that the program does not crash when an illegal money value is provided, and also virtually ‘bags up’ the products purchased. 2
Assignment total (out of 65 marks)
Contribution to grade (out of 20 marks)