Python

Packaging

Packaging in Python involves preparing software for distribution and installation, ensuring that it can be easily deployed across different environments.

Packaging Formats

Source Distribution (sdist)

A source distribution (sdist) is a standard packaging format in Python used for distributing source code. It consists of:

• Archive Format: Typically .tar.gz or .zip.
• Contents: Contains the complete source code of the package.
• Metadata: Includes a setup.py script that defines metadata about the package (e.g., name, version, author, dependencies).
• Purpose: Allows users to build and install the package on their systems by running commands like python setup.py install.
• Flexibility: Provides flexibility in installation configurations and is essential for platforms where pre-built binaries are impractical or unavailable.

Binary Distribution (bdist)

A binary distribution (bdist) in Python is a packaging format that provides pre-built binaries for specific platforms. Key points include:

• Format: Various formats such as Windows installer (.exe), macOS disk image (dmg), or Linux packages (rpm, deb).
• Contents: Contains executable files compiled from source code, suitable for direct installation without needing to compile on the target system.
• Advantage: Offers faster installation compared to sdist by skipping the compilation step.
• Limitation: Less portable than sdist as it is tied to specific operating systems and architectures.

Wheel

A wheel is a newer packaging format (*.whl) introduced to address limitations of sdist and bdist. Key features include:

• Format: Binary distribution format containing compiled Python packages.
• Advantages: Fast installation, supports cross-platform distribution, and eliminates the need for installation from source.
• Metadata: Includes metadata about the package and its dependencies.
• Usage: Preferred format for distributing Python packages on platforms like PyPI due to its efficiency and ease of use.

Egg

"Egg" refers to a distribution format that was popular before the widespread adoption of wheels (*.whl).

• Format: .egg
• Purpose: Eggs were designed as a way to distribute and install Python packages and libraries.
• Contents: An egg is a single-file distribution format that includes the package's code, data files, and metadata.
• Advantages: Similar to wheels, eggs allowed for easy installation of Python packages without needing to compile from source. They provided a standardized way to package and distribute Python code.
• Usage: Eggs were commonly used for distributing and installing Python packages before wheels became more prevalent. They could be installed using tools like easy_install.

Transition to Wheels

• Reason for Decline: Eggs started to decline in popularity due to some limitations and inconsistencies, especially in handling dependencies and conflicts.
• Prevalence of Wheels: Wheels (*.whl) gradually replaced eggs as the preferred binary distribution format in the Python ecosystem. Wheels offered better compatibility, faster installation times, and clearer specifications for package metadata and dependencies.
• Current Usage: While eggs are still technically supported by some tools, wheels are now the recommended and widely accepted format for packaging and distributing Python libraries and applications.

Packaging Tools

Distutils

Distutils is Python's built-in package distribution library. Key features include:

• Basic Functionality: Provides essential tools for packaging and distributing Python modules and extensions.
• Customization: Allows developers to specify package metadata and installation instructions via setup.py.

Setuptools

Setuptools builds on distutils and enhances it with additional features. Key aspects include:

• Dependency Management: Supports specifying dependencies and their versions.
• Extensibility: Enables integration with external libraries and tools.
• Packaging Enhancements: Provides more advanced options for packaging and distribution tasks.