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Working with eggs

Python eggs and how zc.buildout gives you better control over using eggs
Jim Fulton's tutorial for using buildout, originally given at DZUG 2007
Page 2 of 17.
  • Eggs rock!
  • easy_install
    • Easy!
    • Installs into system Python
    • Not much control
  • workingenv makes easy_install much more usable
    • Avoids installing into system Python
    • Avoids conflicts with packages installed in site_packages
    • Really nice for experimentation
    • Easy!
    • Not much control

zc.buildout and eggs

  • Control

    • Configuration driven

      • easier to control versions used

      • always look for most recent versions by default

        handout

        When upgrading a distribution, easy_install doesn't upgrade dependencies,

      • support for custom build options

  • Greater emphasis on develop eggs

    • Automates install/uninstall
    • preference to develop eggs
    handout

    I often switch between develop and non-develop eggs. I may be using a regular egg and realize I need to fix it. I checkout the egg's project into my buildout and tell buildout to treat it as a develop egg. It creates the egg link in develop eggs and will load the develop egg in preference to the non-develop egg.

    (easy_install gives preference to released eggs of the same version.)

    When I'm done making my change, I make a new egg release and tell buildout to stop using a develop egg.

handout
zc.buildout is built on setuptools and easy_install.

zc.buildout current status

  • Actively used for development and deployment

  • Third-generation of ZC buildout tools

    handout

    Our earliest buildouts used make. These were difficult to maintain and reuse.

    Two years ago, we created a prototype Python-based buildout system.

    zc.buildout is a non-prototype system that reflects experience using the prototype.

  • A number of "recipes" available

A Python Egg Primer

Eggs are simple!

  • directories to be added to path

    • may be zipped
    • "zero" installation

  • Meta data

    • dependencies
    • entry points

  • May be distributed as source distributions

    handout

    easy_install and zc.buildout can install source distributions as easily as installing eggs. I've found that source distributions are more convenient to distribute in a lot of ways.

  • Automatic discovery through PyPI

Next: Glossary of Egg Jargon Previous: What is zc.buildout