pythonpackageegg

What is a Python egg?


I'm trying to understand how Python packages work. Presumably eggs are some sort of packaging mechanism, but what would be a quick overview of what role they play and may be some information on why they're useful and how to create them?


Solution

  • Note: Egg packaging has been superseded by Wheel packaging.

    Same concept as a .jar file in Java, it is a .zip file with some metadata files renamed .egg, for distributing code as bundles.

    Specifically: The Internal Structure of Python Eggs

    A "Python egg" is a logical structure embodying the release of a specific version of a Python project, comprising its code, resources, and metadata. There are multiple formats that can be used to physically encode a Python egg, and others can be developed. However, a key principle of Python eggs is that they should be discoverable and importable. That is, it should be possible for a Python application to easily and efficiently find out what eggs are present on a system, and to ensure that the desired eggs' contents are importable.

    The .egg format is well-suited to distribution and the easy uninstallation or upgrades of code, since the project is essentially self-contained within a single directory or file, unmingled with any other projects' code or resources. It also makes it possible to have multiple versions of a project simultaneously installed, such that individual programs can select the versions they wish to use.