Product package layout

Description

Conventions and techniques for organizing the package for an AT product.

Following Zope, Plone and AT’s conventions, the content of our example product pakage will look like this:

- __init__.py
- configure.zcml
- config.py
- interfaces.py
- content
    - __init__.py
    - message.py
- profiles
    - default
- browser
    - __init__.py
    - configure.zcml
    - instantmessage.pt
- tests
    - __init__.py
    - base.py
    - test_setup.py

What is the purpose of these files and directories?

• __init__.py: The usual “Python package” initialization module;
• configure.zcml: Using Zope’s new Configuration Markup Language (ZCML), this file configures the services or behaviour the Zope server needs to load at startup;
• config.py: Provides configuration variables for the product;
• interfaces.py: Where you define interfaces describing what the packages’ classes will do;
• content: Contains the modules providing the implementation of the content types. In this case, it contains the message.py file where the ‘InstantMessage’ class should be defined;
• profiles/default: Contains a set of XML files that are needed to provide the settings that will be used by Plone’s Quick-Installer tool when installing the product within Plone; this is what we call an Extension Profile, an artifact of Zope CMF’s GenericSetup technology. Note that this replaces the old way of doing based on the Extensions/Install. More precisely, since Plone 3.0, you do not need that old-style technique;
• browser: The sub-package where the developer can add specific presentation code such as browser views and templates; the contained configure.zcml is used to provide these components registration.
• tests: Contains the unit tests code for the product.

If you have ZopeSkel installed, you can use the following command to create a similar structure:

paster create -t archetype example.archetype

Now we will go through the files one by one and add what we need to produce our application.