As time goes by, most applications tend to grow heavier and heavier. At some point, any change becomes so expensive that you may not be able to adapt to the needs of your users anymore. This is the sign of a rigid design. Techniques from tactical DDD or clean code do help make your code easier to maintain; however, they only address the surface, not the underlying model.

Thankfully, DDD happens to include a whole section, often overlooked, called "Supple Design". It provides techniques to reach for a design that can easily adapt to future needs. To put it simply: code that is -and will remain- a pleasure to work with.

Are these techniques from 20 years ago still relevant? How do they articulate with other concepts that have appeared since then? In order to answer these questions, let us review each of the principles of Supple Design, illustrate them with some live coding, and see how they make sense as a whole.

This talk includes live coding, based on this code repository: https://github.com/sylvaindecout/supple-design-sandbox.

A first version of this talk was given in 2023 on the occasion of a knowledge sharing day dedicated to DDD at Shodo Paris. It was then presented at Breizhcamp in 2024 (recording available here: https://www.youtube.com/watch?v=ZEcJEhgoi1E).