222.3 Class diagram and CRC cards

This section presents a system-level view of the app design using a class diagram and CRC cards to define class responsibilities and interactions.

Class diagram

The class diagram shows the relationship between the Task and TaskManager classes. It outlines their attributes and methods, giving a high-level overview of the object-oriented structure before implementation begins.

+---------------------+
|      Task           |
+---------------------+
| - title             |
| - description       |
| - due_date          |
| - is_complete       |
+---------------------+
| + mark_complete()   |
| + mark_incomplete() |
| + display_summary() |
| + display_details() |
+---------------------+

        used by

+-----------------------------+
|       TaskManager           |
+-----------------------------+
| - tasks (list of Task)      |
+-----------------------------+
| + add_task()                |
| + list_tasks()              |
| + find_task()               |
| + remove_task()             |
| + display_all_tasks()       |
| + get_incomplete_tasks()    |
| + get_completed_tasks()     |
+-----------------------------+

CRC cards

CRC stands for Class–Responsibility–Collaborator. These cards serve as a planning tool to describe what each class is responsible for and with which other classes it interacts. Below are the CRC cards for this project.

Task

Responsibilities

• Store task data

• Report task details

• Update completion status

Collaborators

• TaskManager (calls methods on Task objects)

TaskManager

Responsibilities

• Store and manage a list of Task objects

• Add, find, and remove tasks

• Display lists of tasks based on user input

Collaborators

• Task (instantiates and manages instances)

Notes on object interaction

The TaskManager acts as the controller, maintaining a list of Task objects and calling their methods as needed. This design keeps individual tasks simple and modular, while allowing the manager class to coordinate complex behaviours.