NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/comp/lang/cplus/11291

Internet Message Format | 1992-07-21 | 1.4 KB

Xref: sparky comp.lang.c++:11291 comp.lang.objective-c:451
Newsgroups: comp.lang.c++,comp.lang.objective-c
Path: sparky!uunet!europa.asd.contel.com!darwin.sura.net!mips!pacbell.com!tandem!UB.com!quack!rmd
From: [e-mail] (Robert M. Diamond)
Subject: Object Oriented Design Question
Message-ID: <[e-mail]>
Followup-To: poster
Organization: The Duck Pond public unix: [phone], log in as 'guest'.
Date: Wed, 22 Jul 1992 01:05:19 GMT
Lines: 19

Hello,
    I am attempting to design a system which reads data in from a
file and writes it back to another file.  Data items can be of various
basic types, like number, string, date or time.  They can be read from
the file or calculated from other read or calculated data items.  They
can be stored in the database (in various ways) or marked for temporary
use only.  The scheme I have come up with is thus:
Have a class "data_item" which can store itself or retrieve its value.
Have subclasses "numeric_data_item," "date_data_item, " etc. which
instantiate the ::store() and ::retrieve() functions.
    The problem is that the typed_data_item either needs to know how
to store itself in each possible way, or the storage_class has to know
how to store each possible type, or I must create classes for the
cartesian product of type and storage class.
    This is my first OOD project, and I would appreciate any ideas
that people can come up with.
    thanx,
    Robert Diamond
    [phone]