Possible to have multiple behaviours?

Questions / Help
,
1

Is it possible to define a behaviour that implements the callback requirements from another behaviour and on top of those some additional ones?

2

It’s very likely possible with some hacking but IMO not out of the box. Behaviours are basically Elixir’s idea of duck typing so they usually aren’t hierarchical.

3

Yes, you can implement as many behaviours as you like as long as their callback requirements do not collide.

1 Like
4

Yeah, I was going through the idea and thinking, well this, is OO - but in fact not really, you’re not defining the implementation just stating what a compliant behaviour must implement.

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5

But you mean, a given module can exercise multiple behaviours, but not that I can define a behaviour such that

defmodule MixedBehaviour do
  @callbacks_from_other_behaviour
  @callback this_module_callback1 :: any()
  #etc
end

I guess I can do __using__ and import both behaviours explicitly there? And then the implementer has to use use instead of @behaviour.