Altering the User Interface

Developers have a couple of different options available to them for modifying the core user interface of the application without modifying the core application itself. These capabilities are added to allow plugins to take the control they need without requiring users to make changes to the application that might make future upgrades more difficult. In this section we will discuss the two primary ways of modifying the core application’s HTML to suit your needs:

Alternate Templates, or “Alt-Templates”

Alt-Templates provide developers with the ability to completely override any template that Movable Type ships with, without hacking the original script in any way. This makes future upgrades less error prone because you don’t need to worry about an upgrade of your core Movable Type system clobbering changes you have made to the core templates. This system works by designating a special directory called alt-tmpl into which can be placed templates you wish to take precedence over their counterparts with the same file name in the tmpl/cms directory.

Transformer Callbacks

Transformer callbacks are a special breed of callback that can be used to dynamically transform the contents of a template before and/or after it has been converted from Movable Type template code into HTML. This system was inspired by an extension to the popular web browser Firefox developed by Aaron Boodman: Greasemonkey. Greasemonkey works on the premise that any page on the web can be [optionally] transformed by a sequence of scripts run against each page. Unlike Greasemonkey which performs these transformations within the browser itself, transformer callbacks are performed by the server, or Movable Type. This means, that these transformations work regardless of what browser your visitors happen to be using at the time.