extending objects at runtime

[marcandre]

I've always avoided extending objects at runtime, like in this example:

class Polymorphic
  def initialize(style: :foo)
    extend Something if style == :bar
    # ...
  end
end

It used to be that performance could be severely impacted but it's not clear it's still the case today (see rubocop/rubocop#8881 )
Style-wise, it seems to complicate things and make introspection / debugging / branch-covering more difficult.

Is that an accepted principle to avoid this (and if so, is it still valid)?

[bbatsov]

I agree that's something to be avoided. I feel similarly about requiring stuff outside of the top-level scope.

[marcandre]

requiring stuff outside of the top-level scope.

I feel this is a very different issue (and I'd love to argue in favor of that if you want to open an issue 😆 )