SDef

sdef is a file format used by Apple's macOS and iOS operating systems to describe the scripting interface of an application. The acronym stands for "Scripting Definition". sdef files are written in XML and provide information about the objects, commands, and properties that an application exposes to scripting clients, such as AppleScript or JavaScript. This allows developers to create scripts that can automate and control the behavior of applications without direct user interaction.

A typical sdef file defines an application's dictionary, which is a hierarchical structure representing the application's data model. It specifies the classes of objects that can be manipulated, their properties (attributes), and the commands that can be executed on them. For instance, an sdef file for a text editor might define a "document" class with properties like "text" and "name," and commands like "save" and "open."

When an application supports scripting, its sdef file is typically embedded within the application bundle. Scripting applications can then access this sdef file to understand how to interact with the target application. This declarative approach simplifies the scripting process by providing a standardized way for applications to communicate their capabilities. Without sdef, scripting would require more complex, application-specific methods for discovering and invoking functionality. Developers can also use tools provided by Apple to generate sdef files from their application's source code, streamlining the scripting integration process.