What is a Python egg

Question

I m new to Python and I m just trying to understand how its 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

User · Answer

Python eggs are a way of bundling additional information with a Python project, that allows the project's dependencies to be checked and satisfied at runtime, as well as allowing projects to provide plugins for other projects. There are several binary formats that embody eggs, but the most common is '.egg' zipfile format, because it's a convenient one for distributing projects. All of the formats support including package-specific data, project-wide metadata, C extensions, and Python code.

The easiest way to install and use Python eggs is to use the "Easy Install" Python package manager, which will find, download, build, and install eggs for you; all you do is tell it the name (and optionally, version) of the Python project(s) you want to use.

Python eggs can be used with Python 2.3 and up, and can be built using the setuptools package (see the Python Subversion sandbox for source code, or the EasyInstall page for current installation instructions).

The primary benefits of Python Eggs are:

They enable tools like the "Easy Install" Python package manager
.egg files are a "zero installation" format for a Python package; no build or install step is required, just put them on PYTHONPATH or sys.path and use them (may require the runtime installed if C extensions or data files are used)
They can include package metadata, such as the other eggs they depend on
They allow "namespace packages" (packages that just contain other packages) to be split into separate distributions (e.g. zope., twisted., peak.* packages can be distributed as separate eggs, unlike normal packages which must always be placed under the same parent directory. This allows what are now huge monolithic packages to be distributed as separate components.)
They allow applications or libraries to specify the needed version of a library, so that you can e.g. require("Twisted-Internet>=2.0") before doing an import twisted.internet.
They're a great format for distributing extensions or plugins to extensible applications and frameworks (such as Trac, which uses eggs for plugins as of 0.9b1), because the egg runtime provides simple APIs to locate eggs and find their advertised entry points (similar to Eclipse's "extension point" concept).

There are also other benefits that may come from having a standardized format, similar to the benefits of Java's "jar" format.

User · Answer

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

User · Answer

Egg  is a single-file importable distribution format for Python-related projects    The Quick Guide to Python Eggs  notes that  Eggs are to Pythons as Jars are to Java       Eggs actually are richer than jars  they hold interesting metadata such as licensing details  release dependencies  etc

User · Answer

The  egg file is a distribution format for Python packages  It   s just an alternative to a source code distribution or Windows exe  But note that for pure Python  the  egg file is completely cross-platform   The  egg file itself is essentially a  zip file  If you change the extension to    zip     you can see that it will have folders inside the archive   Also  if you have an  egg file  you can install it as a package using easy install  Example  To create an  egg file for a directory say mymath which itself may have several python scripts  do the following step     setup py from setuptools import setup  find packages setup      name    mymath       version    0 1       packages   find packages           Then  from the terminal do      python setup py bdist egg   This will generate lot of outputs  but when it   s completed you   ll see that you have three new folders  build  dist  and mymath egg-info  The only folder that we care about is the dist folder where you ll find your  egg file  mymath-0 1-py3 5 egg with your default python  installation  version number mine here  3 5   Source  Python library blog

[python] What is a Python egg?

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