Re: [Caml-list] question: what is the recommended use case of `val` in class type

[Gabriel Scherer <gabriel.scherer@gmail.com>]

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Objects have some private state, and they expose methods that can be called
from the outside. "val" fields correspond to such private state, they are
not accessible from outside and are thus not part of an object's type.

You can always expose a value field to the outside through a "getter"
method to access it (and a "setter" method to mutate it if relevant), but
that is often considered dubious object-oriented style -- it tends to go
against good encapsulation.

On Sat, Jul 2, 2016 at 12:45 PM, Hongbo Zhang (BLOOMBERG/ 731 LEX) <
hzhang295@bloomberg.net> wrote:

> Dear all,
> I have a question about val in class type, is it only useful in
> inheritance?
> for example
> class type text = object val mutable text : string end
> let f (x : text ) = x#text <#m_-4902517353790339526_text>;;
> ^
> Error: This expression has type text
> It has no method text
> Thanks -- Hongbo
>

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