OPS435 Python3 Assignment 2P

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You have successfully designed an algorithm to compute the date which is n day before or after a given date. You have also successfully implemented your algorithm using the Python language by identifying the functions that are needed to perform the computation.

In this assignment, you are going to re-implement the algorithm you have for assignment 1 using python class. You are going to create a new programmer-define object called Date with the appropriate data attributes and function attributes to support the necessary manipulation of date object needed to implement your algorithm for assignment 1.

Your python script must follow the following coding guide:

Class Requirements

Programmer-defined object type: Date

  • Data Attributes: year, month, and day as integer
  • Method attributes: tomorrow(), yesterday(), day_of_week()
  • Operator Overloading:
    • '+': perform addition for two Date() object, and one date object and an integer.
    • '-': perfome substraction for two Date() object, and one date object and an integer
  • Special methods:
    • __init__(self): Date object constructor
    • __repr__(self): return date object as a string in "yyyy-mm-dd" format
    • __str__(self): return date object as a string in "yyyy/mm/dd" format
  • Supporting function:
    • days_to_time(): convert an integer which is n days from epoch (Jan 1, 1970) to a corresponding date object.

Required Modules and Functions

Your python script is allowed to import only the os and sys modules from the standard library and all the built-in functions.


  • Please use python's docstring to document your new python class, class functions and external functions. The docstring should describe 'what' the class is for, what does each class function do, what each data attribute is for.

Authorship Declaration

Your Python code for the Date class and its associated functions must be placed in a single source python file. Please include the following declaration as part of the docstring in your Python source code file (replace "Student Name" with your own name):

OPS435 Assignment 2P - Fall 2019
Program: a1_[student_id].py (replace student_id with your Seneca User name)
Author: "Student Name"
The python code in this file (a1_[Student_id].py) is original work written by
"Student Name". No code in this file is copied from any other source 
except those provided by the course instructor, including any person, 
textbook, or on-line resource. I have not shared this python script 
with anyone or anything except for submission for grading.  
I understand that the Academic Honesty Policy will be enforced and 
violators will be reported and appropriate action will be taken.

Tests and Test results

You must name your class definition python script for Date as a2_class.py. The following tests in an interactive python sessions are for testing your class definition. The assignment test script called "checkA2P.py" should be used once your Date class passes all the interactive tests.

Please review those tests that failed and try to fix it in your class definition to address any bugs you may have.

Test for tomorrow and yesterday methods

Start up an interactive Python session and issue the following python statments:
[raymond.chan@mtrx-node04pd a2p]$ python3
Python 3.6.8 (default, May  2 2019, 20:40:44) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from a2_class import *
>>> dir()
['Date', '__annotations__', '__builtins__', '__doc__', '__loader__', '__name__', '__package__', '__spec__', 'daysb4month', 'int_to_date']
>>> d1 = Date(2019,11,6)
>>> d1.tomorrow()
>>> d1.yesterday()
>>> print(d1.tomorrow())
>>> print(d1.yesterday())
>>> d2 = Date(2019,2,28)
>>> d2.tomorrow()
>>> d2.yesterday()
>>> d3 = Date(2016,2,28)
>>> d3.tomorrow()
>>> d3.yesterday()
>>> d4 = Date(2018,12,31)
>>> d4.tomorrow()

Test for operator overloading '+' and '-'

>>> d1

>>> d2

>>> d1 - d2

>>> d2 - d1

>>> d2 = Date(2019,2,28)
>>> d2

>>> d2 + 1

>>> d2 + 2

>>> d3

>>> d3 + 1

>>> (d3 + 1) - 1

>>> d3 - 1

>>> d4

>>> d4 + 365

>>> d4 - 365

Test for day of the week method

The day of week on Jan 1, 1970 is Thursday. The date.day_of_week() method should return the day of week for the give date in numeric form.
0 - Sun,
1 - Mon,
2 - Tue,
3 - Wed,
4 - Thu,
5 - Friday, and
6 - Saturday
>>> d1 = Date(2019,11,7)
>>> d1
>>> d1.day_of_week()
>>> d2 = d1 + 7
>>> d2
>>> d2.day_of_week()


Create a private repository on github.com under your account

  • name the repository as 'ops435-a2p
  • invite 'rayfreeping' as one of the collaborator to your 'ops435-a2p' repository
  • use this repository for developing the and keeping track of the following text/source code files:
    • The readme.md file to show your progress. Add entry whenever you update any files in this repository.
    • the python class definition named "a2_class.py"
    • the test results produce by the assignment checking script "checkA2P.py". Name it as a2p_results.txt


Task Maximum mark Actual mark
Program Authorship Declaration 5
class block 5
__init__() method 5
__str__() method 5
__repr() method 5
'+' operator 10
'-' operator 10
tomorrow() method 10
yesterday() method 10
day_of_week() function 5
docstring 15
github.com repository 15
Total 100

Due Date and Final Submission requirement

Check with your professor for the due date for your section.

Please submit the following files to blackboard by the due date:

  • your python script, name the file as 'a2_class.py'
  • the output of the checking script checkA2P.py, name the file as 'a2p_results.txt'
  • the 'git log' output for your own repository 'ops435-a2p' on github.com, name the file as 'a2p_gitlog.txt'