Final remarks about descriptors
To wrap up our analysis on descriptors, I would like to share some thoughts in terms of clean code and good practices or recommendations from experience.
Interface of descriptors
When we revisited the interface segregation principle in Chapter 4, The SOLID Principles (the "I" in SOLID), we said that it's good practice to keep the interfaces small, and for that reason, we might want to separate them into smaller ones.
This idea appears here once again, not in the sense of an interface as in an abstract base class, but as the interface that the descriptor itself will present.
As already mentioned, the descriptor protocol entails four methods, but partial implementation is allowed. That means you don't need to implement all of them all the time. In fact, if you only implement the minimal required methods, that would be better.
Most of the time, you'll find that you can address your requirements by only implementing...