Script additions: Rubettes offer a programming interface for setting up some values and user defined hook functions that affect the behaviour of the Rubette. When calculation takes place, the Rubette looks up the value or executes the function and uses its return value. The author of the hook function must only know the programming interface and of course the scripting language FScript. This type of configuration method is heavily used in the current version of the HarmoRubette,⁸

8   See Noll and Garbers (2004) in this volume.

which allows to specify so called harmonic spaces and custom calculation methods. Even the graphical user interface is affected.

Script automation: Because scripts can be used to simulate user actions, or to invoke any method of any programming class, nearly any functionality of Rubato can be accessed by the scripting environment. This possibility can be exploited for semi-automatic software testing, but also to automate a process, where the user would have to iterativly enter values and calculate (and save) some results (e.g. graphics). It was successfully demonstrated with the MetroRubette to show how »the grass grows« in the WeightView window, while the minimal length of local meters decreases. Necessary for a successful application of this method is a knowledge of the (public and private) programming interface of a Rubette.

Patches: A method for applying bug-fixes or for adding custom properties of the frame application or a Rubette, while staying synchronous with the main development process. When starting or when loading a Rubette, Rubato looks for such patches in the file system. To produce a binary patch, a developer compiles the difference-code⁹

9   Not written in FScript but in Objective-C.

into a binary bundle. The Objective-C runtime allows the patch to extent classes or overwrite methods of the Rubette.

Besides these customization possibilities, a developer can write a new Rubette from scratch or based on the source code of an existing OpenSource-Rubette. The availability of the source code furtheron allows to adopt the frame application or to add new Rubette communication or persistence techniques, e.g. for data interchange with databases.

3.2 User and Developer Resources of Support

Similar to Humdrum, there is only limited support available for source code related questions. We also expect more interest in the FScript configuration possibilities, when they are shown to Rubato users, who get in touch with the limitations a graphical user interface imposes on the user actions (script automation), or to those who want to explore own calculation methods in an existing user interface (script additions).

Sources of reference for users and developers are: