Chapter 9. Versioning DSLs

Versioning refers to creating a second version of a language (or a product) that’s compatible with the previous version. Code and other artifacts from the previous version can either run on the new version or there is a well-defined process for moving from one version to the next.

The development of the second version is a critical point in the lifecycle of any language. At that point, you no longer have a blank slate to draw upon; you need to take into account the existing investments in the previous version as well. The alternative would be to stop with a single release, or to abandon all the time and money invested in the previous version. These aren’t choices most people would make.

In this chapter, we’ll lay the foundations we need to create the versioning story for our DSLs. After that, we’ll touch on several different approaches to versioning a language.

Many of the approaches that we’ll discuss in this chapter are applicable to existing languages, but these approaches and techniques are most effective if they’re used when you initially design and build the language. I strongly suggest that, even for small languages, you take the time to consider the versioning strategy you’ll apply.

9.1. Starting from a stable origin

9.2. Planning a DSL versioning story

9.3. Building a regression test suite

9.4. Choosing a versioning strategy

9.5. Applying versioning strategies

9.6. DSL versioning in the real world

9.7. When to version

9.8. Summary