Re: [Caml-list] Smells like duck-typing

[Dario Teixeira <darioteixeira@yahoo.com>]

Hi,

> Uhm sorry, why aren't you going for the object *with* inheritance
> solution? The one you're proposing here is more lightweight than the
> initial one due to the lack of option types, not due to the lack of
> inheritance.
> 
> Can't you just go for:
> 
>   class blurb (id, title, intro) =
>   object
>           method id: int = id
>           method title: string = title
>           method intro: string = intro
>   end
> 
>   class full (id, title, intro, body) =
>   object
>           inherit blurb (id, title, intro)
>           method body: string = body
>   end

While that would indeed involve a little bit of less typing, it's also
conceptually wrong, because a Full story is not a derivation of a Blurb
with an extra field.

Ideally, I should be able to declare a "platonic" Story that includes
all fields that describe a story.  A Full story is just the real-world
clone of the platonic ideal, while a Blurb is a Story with the constraint
that there is no "body" field declared (and so on).

Cheers,
Dario



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