Class Trait.unimplemented

This is a special class constructor that creates an object that satisfies the interface defined by the class type t, but where each of the actual method implementation is a function that returns an error indicating that the method is unimplemented.

This may be useful when you wish to define an object that fails at runtime rather than at compile time, as a base object to extend, such as in:

  let my_vcs =
    object
      inherit Vcs.Trait.unimplemented

      method! ...

      inherit! ...
    end

We do this for example in the implementation of the cli volgo-vcs to define the vcs used for Mercurial repositories.

Note however that in most cases, you'd probably be better off dealing with traits in a static way, by specifying and requiring vcs values that implement the exact set of traits that you need.