When working with Python projects, particularly those containing external or internal dependencies, understanding the differences between `setup.py develop` and `setup.py install` is crucial. These commands, part of the Python setuptools module, offer distinct methods of installing a package. This article explores their functions, use cases, and differences to help you decide which to use for your projects.

setup.py Develop

The `setup.py develop` command is designed to install a package in a development mode. This approach allows you to modify your source code and have the changes immediately reflected in your environment without the need to reinstall the package.

How It Works

• Symbolic Link: When you run `setup.py develop`, setuptools creates a symbolic link to your project directory in the site-packages directory. This means that the Python interpreter directly references your project files.
• Editable Mode: As changes are made in the source files of your project, they are instantly available as part of your Python environment without requiring reinstallation.

Use Cases

• Active Development: Ideal for when you're building or contributing to a package and you want to frequently test changes.
• Library Maintenance: Useful for maintaining a library because updates can be tested immediately.
• Dependency Management: Helpful when you need dependencies in development mode, particularly in complex environments with multiple interdependent projects.

Example

If you are developing a package named `mypackage`, and you've cloned its source, navigate into the directory and run:

• Copying Files: This method copies files from your project's source directory into the site-packages directory, making them accessible to the Python environment.
• Standard Installation: The copied files are static, and any subsequent changes in the project directory require reinstallation to reflect the changes.
• Production Environment: Suitable for deploying applications in a production environment where stability is crucial.
• Non-Development Usage: When simply using a package without plans to modify or develop it further.
• Package Distribution: For users receiving a formally released package version meant for consumption rather than development.