[BLACKBOX] Storing an extended object

From: Douglas G. Danforth <"Douglas>
Date: Mon, 10 Nov 2008 15:20:32 -0800

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I am not quite sure how to implement the Externalize and Internalize
procedures
for objects that are an extension of a base type. If I write an
Externalize procedure
(one for the base and one for the extension) then BB complains. So must
I do something
like the following?

    TYPE
       Base = POINTER TO EXTENSIBLE RECORD(Stores.Store)
           data: INTEGER
           END;
       Sub = POINTER TO RECORD(Base)
          moreData: INTEGER;
          END;

    PROCEDURE (base: Base) Externalize- (VAR wr: Stores.Writer);
    BEGIN
       wr.WriteInt(base.data);
       WITH base: Sub DO
          wr.WriteInt(base.moreData);
       ELSE
       END
    END Externalize;

But now when I internalize what must I do?

This seems cumbersome and not very elegant.
-Doug Danforth

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Received on Tue Nov 11 2008 - 00:20:32 UTC