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Re: Figuring out easier readonly interfaces

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 3 Oct 2013 13:28:10 -0700
Message-ID: <CAAWBYDD5Uwr0B9ps5s=DCVY58-d8sprG204eGR_PjCkcsHi4+w@mail.gmail.com>
To: "Mark S. Miller" <erights@google.com>
Cc: Allen Wirfs-Brock <allen@wirfs-brock.com>, "Robert O'Callahan" <robert@ocallahan.org>, "public-script-coord@w3.org" <public-script-coord@w3.org>
On Thu, Oct 3, 2013 at 12:33 PM, Mark S. Miller <erights@google.com> wrote:
> You forgot to name the readonly one -- it specializes DOMRect by
> guaranteeing that its instances not provide the ability to mutate the
> underlying DOMRect. Given the other names, DOMRectReadOnly or DOMReadOnlyRec
> (did you really mean to omit the "t"?) seem like fine names for the readonly
> subtype.

In Roc's explanation, the readonly one (you can't change the values,
but something else might be able to) is the common superclass.  As he
argued, I'm pretty sure this satisfies LSP - an immutable class is a
valid subclass of a readonly one (you lose nothing, and gain the
ability to depend on the values staying constant), and a mutable class
is also a valid subclass of a readonly one (again, you lose nothing,
but you gain the abiilty to alter the values yourself).

Received on Thursday, 3 October 2013 20:28:56 UTC

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