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Putting it together

Write a CLI app with a menu loop.

Putting the Todo CLI together

All pieces are ready: the tasks list, the add_task, list_tasks and complete_task functions. Now we put them together:

add_task("Buy bread")
add_task("Buy milk")
list_tasks()
complete_task(0)
list_tasks()

This call order shows a typical usage flow. First tasks are added, then listed, one is completed and listed again.

The full flow

A full flow runs like this:

add_task("Buy bread")
add_task("Buy milk")
list_tasks()
complete_task(0)
list_tasks()

The output: first the empty list, then tasks 0 and 1 are listed, then task 0 is updated to "Buy bread [done]" and the list is printed again.

This project is the skeleton of real CLI apps; in real life it can also be used with command-line arguments.

Practice Call the full flow

Add the calls add_task("Buy bread"), add_task("Buy milk"), list_tasks(), complete_task(0) and list_tasks() in order.

Starter code

main.py
# Todo CLI - bos gorev listesi
tasks = []
print(tasks)
def add_task(title):
    tasks.append(title)
def list_tasks():
    for i, t in enumerate(tasks):
        print(i, t)
def complete_task(index):
    if 0 <= index < len(tasks):
        tasks[index] = tasks[index] + " [tamam]"
# Tum akisi cagir

Sample solution

main.py
add_task("Buy bread")
add_task("Buy milk")
list_tasks()
complete_task(0)
list_tasks()

Expected output

[]
0 Buy bread
1 Buy milk
0 Buy bread [done]
1 Buy milk

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which call order is logical?

  • add_task, list_tasks, complete_task Correct answer
  • list_tasks, add_task, complete_task
  • add_task, complete_task, list_tasks
  • complete_task, list_tasks, add_task

Explanation: First add tasks, then list, then complete.

2 Complete the call

Question 
add_task("Buy bread")
add_task("Buy milk")
____()
complete_task(0)
list_tasks()
Answer 
add_task("Buy bread")
add_task("Buy milk")
list_tasks()
complete_task(0)
list_tasks()

Explanation: list_tasks() lists the tasks.

3 Match the project pieces

Term Meaning
tasks = [] Data model
add_task Add
list_tasks List
complete_task Complete

All lessons in Beginner

1 Python basics

  1. What is Python?
  2. REPL and print
  3. Comments
  4. Indentation blocks
  5. python -c and scripts
  6. Summary - Python basics

2 Variables

  1. Variable assignment
  2. Multiple assignment
  3. Naming variables
  4. id and type
  5. Swapping variables
  6. Summary - Variables

3 Data types

  1. int and float
  2. bool
  3. str basics
  4. None
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add/subtract
  3. Multiply/divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic
  2. Comparison
  3. Logical
  4. Bitwise
  5. Membership and identity
  6. Summary - Operators

6 String basics

  1. f-string
  2. Concatenation
  3. str.format
  4. Raw strings
  5. Triple-quote
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. elif and else
  3. Nested if
  4. Truthiness
  5. Conditional expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. range
  3. The while loop
  4. break and continue
  5. Loop else
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Lists

  1. Declaring lists
  2. Index and slice
  3. List methods
  4. in and count
  5. Sorting lists
  6. Summary - Lists

11 List comprehension

  1. Comprehension basics
  2. Filtered comprehension
  3. Dict and set comprehension
  4. Nested comprehension
  5. Generator expression
  6. Summary - List comprehension

12 Tuple, set and dict

  1. Tuple
  2. Set
  3. Dict basics
  4. Dict methods
  5. Dict comprehension
  6. Summary - Tuple, set and dict

13 Functions

  1. def
  2. return
  3. Docstring
  4. Default parameters
  5. *args and **kwargs
  6. Summary - Functions

14 Function parameters

  1. Positional parameters
  2. Keyword parameters
  3. Keyword-only
  4. Positional-only
  5. Type hints basics
  6. Summary - Function parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string methods

  1. split and join
  2. strip, lstrip, rstrip
  3. replace
  4. find and index
  5. startswith, endswith
  6. Summary - Advanced strings

17 Input and output

  1. input()
  2. int/float conversion
  3. print parameters
  4. f-string formatting
  5. sys.argv
  6. Summary - Input and output

18 Error handling

  1. try/except
  2. else and finally
  3. raise
  4. Exception hierarchy
  5. Custom exceptions
  6. Summary - Error handling

19 Modules

  1. import
  2. from import
  3. as alias
  4. __name__ == '__main__'
  5. Standard library
  6. Summary - Modules

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together