There are several competing ways to start on a new extender:
A free Java application called ArgoUML lets you draw out your extensions as a UML diagram, which you run through a code generator, ArchGenXML, to create your actual product. However, ArgoUML is notoriously buggy and confusing to use, and the simplicity of most extenders makes it a bad trade-off.
The ZopeSkel templates for the
paster
code generator, which we will use in the Going Live and Styling Your Site chapters, include one for making Archetypes types. Rather than taking a UML file as input,paster
asks a series of questions via the command line and then lays out the skeleton of a product. It then provides a command-line interface for adding functionality. A future version of FSD will include a template for making FSD extenders using this process. At the moment, however, there remain some kinks to work out; the version in development works, but it yields a somewhat complex result that is difficult to learn...