I just use a struct literal, and then I have the type define a `func (t *Thing) ready() error { ... }` method and call the ready method to check that its valid.

I just use a struct literal, and then I have the type define a `func (t *Thing) ready() error { ... }` method and call the ready method to check that its valid. I prefer this over self-referential options, the builder pattern, supplying a secondary config object as a parameter to a constructor, etc.