Learning GNU Emacs, 3rd Edition

Building an Automatic Template System

You're probably starting to see how all these tools can be put together in really powerful ways. Most of the rest of the chapter consists of examples of building relatively real and useful new features for Emacs. You can use them as learning tools for how to build your own, and you may be able to use them as-is, or with a little tweaking, in your own daily work.

The example we're about to look at is something that one of the authors developed over a decade ago to help with the tedium of creating new files in development projects where a certain amount of structure and standard documentation were always needed. Many coding and writing projects have this characteristic; each file needs some boilerplate, but it needs to be adjusted to the details of the file. Emacs turned out to be very much up to the task of automating a lot of the drudge work, and this template system has been heavily used ever since.

Most of the code in this example should already make sense to you. A couple of aspects that will be explained more thoroughly in the next section about programming a major mode. In particular, don't worry too much yet about exactly what a "hook" function is, or funcall. For now it's sufficient to know that the file-not-found-hook allows us to run code when the user uses find-file to open a file that doesn't exist yet (exactly the time at which we'd like to offer our template services).

Before launching into the code, it's worth looking at an example ...