Create folderish classes

Created by . Last modified on 2003/08/05.

This how-to describes making a folderish class. There are several how-to's already on how to make simple objects such as the Boring Product (1) and the Minimal Product(2).

One useful object though that can create a very powerful product is the Folderish object and this how-to covers the ins and outs of creating a simple Folderish based product, Simple Posting (3).

Simple Posting is a class to create the kind of postings that people put on articles such as on slashdot.org (but hopefully more useful comments). The basic structure is that a user can post a comment on a article. They can post a comment about a comment or on the original article. And so on, which can simply be represented by a simple tree of folders from the originating article down.

Why a folderish object?

Why not? A folderish object has the ability to hold objects, a non-folderish object hasn't. A non-folderish object can render dtml from "data", where as this can be mind-bendingly annoying for a folderish object. This can turn into a bit of a science project, avoid it.

The extra overhead of folderish object is so minimal that I have found unless your object renders dtml from user input (eg: DTML Document), use a folderish object. I have one site that scales very nicely with about 10,000 nested folderish objects.

How do I make one?

Very similar to a normal object...

1. create a folder and put in it __init__.py

__init__.py
...

2. start off your class

Posting.py
... header stuff

What to inherit from?

As you move "up" the hierarchy towards more basic objects such as ObjectManager you lose functionality that people have already coded in stuff such as Folder. OFS.Folder is a great class that includes most of the things you need. I normally just inherit off that and I would suggest you do the same.

References

1. Boring product
2. Minimal product
3. Simple Posting