Day 3

Working with Files

Let Claude read, write, and refactor files in your project — the real superpower begins here.

0 / 6 tasks

Claude as a coding partner

When you run `claude` inside a project directory, it can read any file you reference, create new files, and make precise edits. Claude understands your full project context, not just snippets.

Referencing files in REPL

bash

cd my-project
claude

> Read main.py and explain the architecture
> Refactor the `process_data` function to use async/await
> Write unit tests for every function in utils.py
> Add type hints to all functions in models.py

Generating new files

bash

claude
> Create a new file called config.py with Pydantic settings for: DATABASE_URL, SECRET_KEY, DEBUG, and ALLOWED_HOSTS
> Now create a .env.example file with placeholder values for those settings
> Create a README section explaining the configuration

💡 Claude won't blindly overwrite files without showing you the diff first. Always review changes before approving them.

Practice Tasks

0 / 6

Ask Claude to read a file easy

In a project, start Claude and ask it to explain the architecture of your main file.

Generate a new file easy

Ask Claude to create a `helpers.py` module with 3 utility functions relevant to your project.

Refactor existing code medium

Pick a function that could be cleaner. Ask Claude to refactor it and review the proposed diff.

Add type hints medium

Ask Claude to add Python type hints to all functions in a file and review the changes.

Write unit tests medium

Ask Claude to generate a test file for an existing module. Run the tests and fix any failures with Claude's help.

Find bugs hard

Ask Claude to review a file for potential bugs, edge cases, or security issues. Implement at least one fix.

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