We have written a custom code generator mix task. Working with external APIs, we wrote the same set of API provider-specific modules every time a new integration would be added.

The generator is simple/naive in its implementation, but it saves hours of repetitive copying, pasting and adjusting. It spits out the modules alongside some unit tests and prints out a to-do list of tasks that need to be performed manually.

The task itself was maybe half a day‘s work and has paid for that time investment many times over by now. (Refactoring the code base to a point where it‘s extensible in a way that is so straightforward that a codegen is even an option was naturally a bit more involved, but that is a different story )

That kind of story makes for an invaluable article for many still learning and improving in their Elixir journey…

Custom tasks are good to formalize data migrations that should run as part of a multi-step migration strategy when changing DB and Ecto schema structures in large database projects. It’s a good way to plan for, check, execute, and test data changes at every step. Then they can be moved to a history branch for posterity when the migrations succeed.

I didn’t even consider the idea of leveraging it in with respect to third party integration.

Seems it’s easy to get bogged down earlier on with connecting the dots internally, I forget that the value of almost any non-trivial program is from interaction with outside processes/APIs and need to grow my mindset to consider that potential from the beginning.