17.4.07. Reuse and non use

We’ve been using Zope 3 in earnest for just over a year and a half now. I would like to report that in that year and a half our little company has achieved more re-use than at any time in our history. This is real re-use too: libraries of tools and objects that are easily shared among both horizontal and vertical markets, yet customized for each customer as needed. Benefits for one are fairly easily shared with all.

In the Zope 2 days, we tried hard to achieve this. But we were constantly having to re-invent the kind of architecture that I believe really makes this work: adaptation, which also brings dynamic view binding, dynamic UI generation (ie - registering a ‘tab’ for a particular object / interface and having it show up in the UI as necessary, etc. We had to spend a lot of time making the frameworks that would let us make frameworks.

“Frameworks for making frameworks?” - you heard right. Let’s face it: most web work is custom development. Sometimes custom development is best served by tools like Ruby on Rails or Pylons, or even by plain old PHP. But sometimes you know you’re going to have at least five customers all needing variations on the same thing in the coming months; and potentially more after that. You’re going to need to at least make a library or two.

See, Model-View-Controller isn’t just about “separating business logic from presentation”. It’s about separating it in a way that you can take business objects and logic (the ‘model’ layer; or models and services) and put more than one view on them. And by “more than one view”, I don’t mean “more than one template.” I mean putting wholly different user interfaces on it. I mean being able to take a base library and override a few select options (or many select options) as they appeal to a customer.

We tried to achieve this on some of our Zope 2 products, but it was hard to extract frameworks. We did OK, however, but I think that the most re-use we ever got was about three or four customers on one toolkit. That was over a three or four year span. We re-used patterns and snippets quite often, but it took a lot of work to extract an e-commerce toolkit from a particular customer’s site, and more work still to make it adaptable and workable for different customer requirements.

In the year and a half since using Zope 3 full time, we’ve had double that - and with far greater results. It’s not an easy system to just start using from scratch, but it can be quite worth it.

Being back at work on some legacy Zope 2 projects has made me all the more appreciative.

By the way: for a simpler Zope 3 development experience, check out Grok.