Demo Basic Code Completion

In this lesson we’ll explore basic code completion with GitHub Copilot inside an editor and Copilot Chat. Using a small Python project, you’ll see how Copilot suggests completions, responds to docstrings and type hints, and helps diagnose and fix common runtime errors.

This tutorial covers practical Copilot usage patterns for Python: completing boilerplate, implementing functions from docstrings, generating list comprehensions, handling file errors, and using Copilot Chat to debug exceptions. Follow along by creating a simple main.py.

Relevant links:

1) Create a Python file

Create a new file for this demo:

jeremy@Jeremys-Mac-Studio fakedatagenerator % touch main.py
jeremy@Jeremys-Mac-Studio fakedatagenerator %

This minimal step prepares the editor for Copilot to begin suggesting completions.

2) Hello World

Start with a simple main entry point. Copilot often recognizes this pattern and suggests the complete implementation immediately:

def main():
    print("Hello, World!")


if __name__ == "__main__":
    main()

Run it to confirm everything works:

jeremy@Jeremys-Mac-Studio fakedatagenerator % python3 main.py
Hello, World!
jeremy@Jeremys-Mac-Studio fakedatagenerator %

Tip: For trivial patterns like this, accept the suggestion or regenerate if you want stylistic variations.

3) Generate a factorial function from a docstring

Copilot leverages function names, type hints, and docstrings to infer implementations. For example, provide a brief signature and docstring:

def factorial(n: int) -> int:
    """Returns the factorial of a given number."""

Copilot commonly completes it as a recursive solution:

def factorial(n: int) -> int:
    """Returns the factorial of a given number."""
    if n == 0:
        return 1
    return n * factorial(n - 1)

If you prefer an iterative approach, Copilot may instead generate a loop-based implementation depending on surrounding code and your editing history.

4) Extract usernames from a list of dictionaries

Copilot recognizes common Python idioms such as list comprehensions. When you start typing, it often suggests the full comprehension:

users = [
    {"name": "Michael", "id": 1},
    {"name": "Sanjeev", "id": 2},
    {"name": "Jeremy", "id": 3},
]

usernames = [user["name"] for user in users]

# print each username
for username in usernames:
    print(username)

Run it to verify output:

jeremy@Jeremys-Mac-Studio fakedatagenerator % python3 main.py
Michael
Sanjeev
Jeremy
jeremy@Jeremys-Mac-Studio fakedatagenerator %

Copilot speeds up repetitive patterns by completing common idioms like this.

5) Gracefully handle missing files with try/except

When interacting with files, Copilot often suggests handling FileNotFoundError explicitly. Example:

try:
    with open("data.txt", "r") as f:
        data = f.read()
except FileNotFoundError:
    data = "No data available"

print(data)

If you prefer broader error coverage, Copilot can also suggest a general exception handler:

try:
    with open("data.txt", "r") as f:
        data = f.read()
except Exception as e:
    print(e)
    data = "default data"

print(data)

Recommendation: choose the more specific exception when you know which errors to expect; use general handlers only when necessary.

6) Using requests and fixing an AttributeError

If you import requests but forget to install it, your editor may offer a quick fix to install the package. Example pip installation:

(venv) jeremy@Jeremys-Mac-Studio fakedatagenerator % pip install requests
Collecting requests
  Downloading requests-2.32.3-py3-none-any.whl (64 kB)
Installing collected packages: requests
Successfully installed requests-2.32.3
(venv) jeremy@Jeremys-Mac-Studio fakedatagenerator %

A common mistake is calling a non-existent method (e.g., requests.test), which raises an AttributeError:

import requests

response = requests.test("https://api.github.com")  # incorrect
print(response.status_code)

Traceback example:

(venv) jeremy@Jeremys-Mac-Studio fakedatagenerator % python3 main.py
Traceback (most recent call last):
  File "/Users/jeremy/Projects/fakedatagenerator/main.py", line 3, in <module>
    response = requests.test("https://api.github.com")
                   ^^^^^^^^^^^
AttributeError: module 'requests' has no attribute 'test'
(venv) jeremy@Jeremys-Mac-Studio fakedatagenerator %

Copilot typically suggests replacing the incorrect call with requests.get and adding a safe network exception handler:

import requests

try:
    response = requests.get("https://api.github.com")
    print(response.status_code)
except requests.exceptions.RequestException as e:
    print(f"An error occurred: {e}")

This both corrects the method and adds robust handling for network-related errors.

Screenshot of a GitHub Copilot menu overlaid on a code editor, with "Status: Ready" highlighted and a hand cursor pointing at "GitHub Copilot Chat." The menu shows options like Open Completion Panel, Disable Completions, Edit Settings, and View Copilot Documentation.

7) Using Copilot Chat to diagnose issues

Open Copilot Chat, paste the error message and the relevant code, and Copilot Chat will usually return a diagnosis and suggested edits. When applying suggestions, you typically have three options:

Apply in Editor — Copilot modifies the file directly.
Insert at Cursor — Copilot inserts the suggestion at the current cursor location.
Copy — copy the suggestion and paste it manually.

Be cautious when using “Apply in Editor” — in some cases Copilot may change more than you expect. Review diffs before accepting changes.

For the requests.test error above, Copilot Chat commonly suggests switching to requests.get and wrapping the call in a try/except for requests.exceptions.RequestException, as shown earlier.

Reference table: patterns and Copilot behavior

Pattern	What Copilot suggests	Example
Boilerplate / entry point	Complete `main()` and `if __name__ == "__main__":`	`def main(): ...`
Docstring + type hints	Implementation inferred from description	`def factorial(n: int) -> int:`
Collection transformations	Full list comprehension or generator	`usernames = [user["name"] for user in users]`
File handling	Specific exceptions like `FileNotFoundError`	`except FileNotFoundError:`
Network calls	Correct HTTP method + `requests` exceptions	`requests.get(...); except requests.exceptions.RequestException`

Summary

GitHub Copilot quickly completes common code patterns (Hello World, factorial, comprehensions).
Docstrings and clear type hints improve suggestion accuracy.
Copilot recommends specific exceptions (e.g., FileNotFoundError) and practical error-handling idioms.
Use Copilot Chat for diagnosing runtime errors, but always review suggested edits before applying them.
When an edit is overly broad, copy and paste the suggested change manually to retain control.

By practicing with small examples like these, you’ll learn how Copilot streamlines repetitive tasks and helps diagnose issues without relinquishing control of your code.

Introduction to GitHub Copilot

Core Features

Using Copilot Efficiently

Demo Basic Code Completion

1) Create a Python file

2) Hello World

3) Generate a factorial function from a docstring

4) Extract usernames from a list of dictionaries

5) Gracefully handle missing files with try/except

6) Using requests and fixing an AttributeError

7) Using Copilot Chat to diagnose issues

Reference table: patterns and Copilot behavior

Summary

Links and further reading

Watch Video

​1) Create a Python file

​2) Hello World

​3) Generate a factorial function from a docstring

​4) Extract usernames from a list of dictionaries

​5) Gracefully handle missing files with try/except

​6) Using requests and fixing an AttributeError

​7) Using Copilot Chat to diagnose issues

​Reference table: patterns and Copilot behavior

​Summary

​Links and further reading

Watch Video

1) Create a Python file

2) Hello World

3) Generate a factorial function from a docstring

4) Extract usernames from a list of dictionaries

5) Gracefully handle missing files with try/except

6) Using requests and fixing an AttributeError

7) Using Copilot Chat to diagnose issues

Reference table: patterns and Copilot behavior

Summary

Links and further reading