Re: [BLACKBOX] Exporting records / record fields question

From: [at]} <Rex>
Date: Fri, 30 Jul 2010 08:52:12 -0500

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At 08:12 AM 7/28/2010, Alexander Iljin wrote:
> The real-world scenario for this is when you don't want to publish
>the record type so that client modules can't make extensions.

>...I use this feature to control extensibility in my Oberon-2 programs.
> Also, you can create enumerations with objects like week days:
>TYPE
> WeekDay = POINTER TO RECORD dayNumber-: INTEGER END; (* the type is
>not published *)
>VAR
> monday-, tuesday-, ... : WeekDay; ....

        Amazing! Or in colloquial English, awsome.


Chris Burrows wrote:
>In Section 8.3.1 it states: "Note that when fields in a record r are
>exported, r should be exported too".

        A rule that's apparently not in the language specification. I think the language specification takes precedence.

        This is not the first time someone has found a useful loophole in a specification. Unless some harm can be identified, it is usually a mistake to attempt to plug loopholes in later specifications, since such attempts break code. I really, really hate changes that break code.

Sincerely,
Rex Couture

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Received on Fri Jul 30 2010 - 15:52:12 UTC