Project: To-Do List Manager

Build a small task manager with classes that add, complete, remove, and report tasks.

20 min read 10 quiz questions

Stage 1: Make a Task class

A class is a blueprint for objects. Each Task will store a title and whether it is done. Its __str__ method chooses the text shown by print().

Stage 1: Represent one task

class Task:
    def __init__(self, title):
        self.title = title
        self.done = False

    def __str__(self):
        status = "done" if self.done else "todo"
        return f"{self.title} [{status}]"

task = Task("Buy milk")
print(task)

The new task starts with done set to False. Python calls __str__ when the task is printed.

Stage 2: Store tasks in a TodoList

A second class can keep a list of Task objects. Its add method creates and stores a task.

Stage 2: Add tasks to a list

class Task:
    def __init__(self, title):
        self.title = title
        self.done = False

    def __str__(self):
        status = "done" if self.done else "todo"
        return f"{self.title} [{status}]"

class TodoList:
    def __init__(self):
        self.tasks = []

    def add(self, title):
        self.tasks.append(Task(title))

todo = TodoList()
todo.add("Write code")
todo.add("Read notes")
for task in todo.tasks:
    print(task)

self.tasks is a list of objects. Each call to add appends one new Task.

Stage 3: Complete and remove tasks

Methods can search the task list. Mark a matching task done, or build a new list that leaves a matching task out.

Stage 3: Complete and remove tasks

class Task:
    def __init__(self, title):
        self.title = title
        self.done = False

    def __str__(self):
        mark = "x" if self.done else " "
        return f"[{mark}] {self.title}"

class TodoList:
    def __init__(self):
        self.tasks = []

    def add(self, title):
        self.tasks.append(Task(title))

    def complete(self, title):
        for task in self.tasks:
            if task.title == title:
                task.done = True

    def remove(self, title):
        self.tasks = [task for task in self.tasks if task.title != title]

todo = TodoList()
todo.add("Write code")
todo.add("Read notes")
todo.add("Buy fruit")
todo.complete("Write code")
todo.remove("Buy fruit")
for task in todo.tasks:
    print(task)

Completing changes one task object's done value. Removing rebuilds the list without the matching task.

Stage 4: Finish the to-do list manager

Add a list_tasks method for the numbered view and a final report that counts completed tasks.

Stage 4: Complete to-do list manager

class Task:
    def __init__(self, title):
        self.title = title
        self.done = False

    def __str__(self):
        mark = "x" if self.done else " "
        return f"[{mark}] {self.title}"

class TodoList:
    def __init__(self):
        self.tasks = []

    def add(self, title):
        self.tasks.append(Task(title))

    def complete(self, title):
        for task in self.tasks:
            if task.title == title:
                task.done = True
                return

    def remove(self, title):
        self.tasks = [task for task in self.tasks if task.title != title]

    def list_tasks(self):
        print("To-do list:")
        for number, task in enumerate(self.tasks, start=1):
            print(f"{number}. {task}")

todo = TodoList()
todo.add("Write code")
todo.add("Read notes")
todo.add("Buy fruit")
todo.complete("Write code")
todo.remove("Buy fruit")
todo.list_tasks()
completed = sum(task.done for task in todo.tasks)
print(f"Completed: {completed} of {len(todo.tasks)}")

The final report lists the remaining Task objects and counts the ones marked done. The manager now adds, completes, removes, and lists tasks.

Key points

A class is a blueprint for objects with data and methods.
__str__ controls how an object appears when printed.
A TodoList can store Task objects in a list.
Methods can add, complete, remove, and list tasks.
sum() can count True done values in a task list.

Worked example

A tiny task manager: tasks are dictionaries in a list, so each carries a title AND a done flag.

Example

tasks = [
    {"title": "Math homework", "done": True},
    {"title": "Buy eggs", "done": False},
]
pending = [task["title"] for task in tasks if not task["done"]]
print(pending)

How it works, step by step

Each task is a dict — fields accessed by name.
The comprehension filters on the done flag.
Only unfinished titles survive.

References & Further Reading

Related entries from PyLabs's own reference library.

append() (Add a single item to the end of the list.)
copy() (Make a shallow copy of a list.)
sort() (Sort the elements of the list in ascending or custom order.)

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Practice exercise

Not passed yet

Create a Task class with title, done, and __str__ that returns [x] title when done and [ ] title otherwise. Create a TodoList class with add and complete methods. Add Plan trip, complete it, and print exactly [x] Plan trip.

# Define Task and TodoList
# Add and complete the requested task

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