Call super's initializer

[marten]

If Virtus is included in a module, that module might want to add additional initialization, but without a call to super it can't.

It might be I added tests in the wrong places. If that or anything else is wrong, please let me know.

Example use case:

module OurGem
  include Virtus
  def initialize(*args)
    perform_authorization_check
  end
end

Caveats

I'm not too happy about explicitly expecting that no arguments are expected for super. However, if Virtus is included in a simple class with no (explicit) ancestor the ancestor will be Object, whose #initialize takes no arguments. So without the parentheses after super() the most basic use case would fail. This does however mean that the user still can't have:

class Supr
  def initialize(attributes = {})
    # do stuff with the initial attributes hash
  end
end

class Child
  include Virtus
end

I don't know if it's worth muddying up the code with arity checks. If there's an elegant solution, I'd love to hear it.

[dkubb]

I think as a general policy if we add a method that is defined in an ancestor, we should consider calling super. It doesn't mean we always do it, but I think it should be considered.

In this case I agree that we should at least call super(). Like @marten, I'm not sure if we should do arity checks and pass up args based on the arity; the arguments passed into the child method could be completely different from the parent. As a general rule I think it's better to respect the original method interface, since it allows for substitutability, but an #initialize is probably one of the exceptions to the rule.

[solnic]

I'm planning to extract the constructor part into a separate extension. The contract will be that if you have your own constructor then you don't use virtus' one. This will make things simpler and more obvious. Having said that I don't think I want to complicate the code and make it "smart" wrt initialize and super.

[marten]

@solnic So do you want to wait for the extraction before merging this? Any way I can help out with that?

[solnic]

@marten yes I want to extract that piece into a separate module and fix super there. You can of course tackle that if you want :)

[solnic]

I'm gonna call it as fixed because you can now skip including virtus' constructor.

[mbj]

@solnic I take this one as signal to finally implement this in concord also ;)

[mbj]

@solnic And thx. Helps in one of my virtus use cases!

[solnic]

@mbj good to know :) so FYI you can do it like that include Virtus.model { |c| c.constructor = false }

[mbj]

@solnic Good idea!