> ## Documentation Index
> Fetch the complete documentation index at: https://python4ai.codewithsiva.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Formatting with Ruff

> Automatically format and lint your Python code

## What is Ruff?

Ruff is a modern Python tool that's incredibly fast and combines multiple tools in one:

* **Linting** - Finding issues and potential errors
* **Formatting** - Fixing code style automatically
* **Import sorting** - Organizing imports cleanly

It's beginner-friendly with clear error messages and works seamlessly with VS Code.

<Note>
  A **linter** checks your code for style issues and potential errors. A **formatter** automatically fixes these issues for you.
</Note>

## Install Ruff in VS Code

1. Open VS Code
2. Press `Ctrl+Shift+X` (Windows/Linux) or `Cmd+Shift+X` (Mac)
3. Search for "Ruff"
4. Install the official Ruff extension by Astral

<Note>
  The Ruff extension replaces older tools like Pylint, Black, and isort. You only need this one extension.
</Note>

## Enable format on save

Let's make VS Code automatically format your code when you save:

1. Press `Ctrl+,` (Windows/Linux) or `Cmd+,` (Mac) to open settings
2. Search for "format on save"
3. Check the box for "Editor: Format On Save"
4. Search for "default formatter"
5. Set "Python > Formatting: Provider" to "Ruff"

## See it in action

Here's messy code before formatting:

```python theme={null}
import os
def   calculate_total(items):
    total=0
    for item in items:
        total+=item['price']*item['quantity']
    return total

shopping_cart=[{'name':'apple','price':0.5,'quantity':6},{'name':'banana','price':0.3,'quantity':8}]
print(calculate_total(shopping_cart))
```

After saving with Ruff (automatic):

```python theme={null}
import os


def calculate_total(items):
    total = 0
    for item in items:
        total += item["price"] * item["quantity"]
    return total


shopping_cart = [
    {"name": "apple", "price": 0.5, "quantity": 6},
    {"name": "banana", "price": 0.3, "quantity": 8},
]
print(calculate_total(shopping_cart))
```

Ruff automatically:

* Separated imports
* Added proper spacing
* Fixed indentation
* Made quotes consistent
* Formatted the list for readability

<Tip>
  If formatting doesn't work on save, right-click in your Python file and select "Format Document". This should trigger Ruff manually.
</Tip>

## Common formatting rules

Ruff follows Python's style guide (PEP 8) automatically:

* 4 spaces for indentation
* Spaces around operators (`x = 1`, not `x=1`)
* Two blank lines between functions
* Maximum line length of 88 characters

You don't need to memorize these - Ruff handles them for you!

## Understanding linting errors

Ruff will underline code issues in your editor:

```python theme={null}
# Unused imports (Ruff warns you)
import os
import sys

# Only using one
print("Hello")
```

Hover over underlined code to see:

* What the issue is
* Why it matters
* How to fix it

<Tip>
  Don't ignore linting warnings! They help you write better code and catch bugs early.
</Tip>

## What's next?

With Ruff set up, your code will always look professional and follow best practices automatically.