NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part1/5119

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From: [e-mail] (G. Patrick Sand)
Newsgroups: comp.lang.c++
Subject: Re: simple design question
Date: 2 Feb 1996 16:34:42 GMT
Organization: Hughes Aircraft (EOSDIS)
Message-ID: <4etef2$[e-mail]>
References: <[e-mail]>
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In article <[e-mail]>, [e-mail] says...
>
>This is a design question, not a syntax question, so forgive the pseudo-
>code.
>
>I'm trying to design/write a class for complex file I/O (I'll state it
>in simple terms here).
>
>I want to use it like this:
>        object.Open("xxx")
>        for(...){
>          object.Read(stuff);
>        }
>        object.Close();
>
>But I want to also have a single function that will Open/Read/Close in a
>single operation:
>        object.GetData("xxx",stuff);
>

Okay, the first question is this:

1. Do you want to reuse the open/close/read semantics in other classes?

If so, make it a separate class and use inheritance to add it to classes
where you wish to do complex I/O.  If not, just make them methods in the
desired class.  I recommend that if you have 2 or more classes which will
do this I/O create the I/O operations as a separate class and
inherit--this is one of the maintenance blessing C++ and OOA/D confers on
you...if you use it...

The second question is this:

2. Why not use the iostreams/fstreams stuff?  It does deal with
clashes-like calling Open() then GetData()...although you will need to do
some checking... This can be put into a separate class or built into the
methods and save you some hassles...iostreams is very powerful, and a bit
daunting at first, but as I'm learning it I am starting to prefer it over
the printf/scanf functions I mastered in C...

You might also want to have a separate class for the I/O and include
state variables (i.e., attributes in OOD-speak) to indicate if you have a
file, have it open, or have closed it....It looks like a string (or char
pointer) for the filename and an int for SELECTED/OPENED/CLOSED/NONE...

Might as well experiment with this stuff now, it's cheap (just time and
electricity on your computer) and will benefit you greatly as you dig
deeper into C++....

BTW, I'm going to finally break down and buy and book on iostreams; I've
reached the point where my needs exceed the usual discussions in the C++
books...

Hope this helps...
--
G. Patrick Sand
[e-mail]
[e-mail]
[phone]
"Travel Light But Right..."
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