[Caml-list] private object constructor?

[Caml-list] private object constructor?

[Steffen Smolka]

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Hi,

Is it possible to expose an object or class type in OCaml without exposing
the constructor, i.e. the ability to construct objects of the type? OCaml
supports private ADTs and type synonyms, but the private keyword doesn't
seem to work with classes or objects.

Thanks,
-- Steffen

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Re: [Caml-list] private object constructor?

[Ivan Gotovchits]

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Hi Steffen,

Your question contains the answer :) You can indeed expose an object type
and a class type without exposing the class.

module Example : sig
  class type t = object
      method print : unit
    end
end = struct
    class t = object
      method print = print_endline "yep"
    end
  end

The class implementation will not be exposed, so `new Example.t` will say
`Unbound class Example.t`. But, the class type and object type will be
exposed,
e.g, you may say `type printable = Example.t` (yes, class type declaration
declares both the type and the class type).

Regards,
Ivan


On Mon, Feb 13, 2017 at 1:23 PM, Steffen Smolka <smolka@cs.cornell.edu>
wrote:

> Hi,
>
> Is it possible to expose an object or class type in OCaml without exposing
> the constructor, i.e. the ability to construct objects of the type? OCaml
> supports private ADTs and type synonyms, but the private keyword doesn't
> seem to work with classes or objects.
>
> Thanks,
> -- Steffen
>

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Re: [Caml-list] private object constructor?

[Steffen Smolka]

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Thanks, this works :)

-- Steffen

On Mon, Feb 13, 2017 at 1:57 PM, Ivan Gotovchits <ivg@ieee.org> wrote:

> Hi Steffen,
>
> Your question contains the answer :) You can indeed expose an object type
> and a class type without exposing the class.
>
> module Example : sig
>   class type t = object
>       method print : unit
>     end
> end = struct
>     class t = object
>       method print = print_endline "yep"
>     end
>   end
>
> The class implementation will not be exposed, so `new Example.t` will say
> `Unbound class Example.t`. But, the class type and object type will be
> exposed,
> e.g, you may say `type printable = Example.t` (yes, class type declaration
> declares both the type and the class type).
>
> Regards,
> Ivan
>
>
> On Mon, Feb 13, 2017 at 1:23 PM, Steffen Smolka <smolka@cs.cornell.edu>
> wrote:
>
>> Hi,
>>
>> Is it possible to expose an object or class type in OCaml without
>> exposing the constructor, i.e. the ability to construct objects of the
>> type? OCaml supports private ADTs and type synonyms, but the private
>> keyword doesn't seem to work with classes or objects.
>>
>> Thanks,
>> -- Steffen
>>
>
>

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