Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!meaddata!rob
From: rob@meaddata.com (Robert E. Lancia)
Newsgroups: comp.lang.c
Subject: Re: Info Hiding in C
Keywords: Hiding
Message-ID: <3997@meaddata.meaddata.com>
Date: 18 Apr 91 14:38:32 GMT
References: <1991Apr17.004044.22940@ux1.cso.uiuc.edu> <16645@chaph.usc.edu>
Sender: usenet@meaddata.com
Organization: Mead Data Central, Dayton OH
Lines: 41

In article <16645@chaph.usc.edu> jeenglis@alcor.usc.edu (Joe English) writes:
>unicorn@uxh.cso.uiuc.edu (Harry E Miller) writes:
>
>>I wish to include optional information hiding within this library,
>>so that the programer can only get string information from a
>>function (not a macro!).
>> [...]
> [...]
>struct _string {
>    ...     /* same as above */
>};
>
>typedef char String[sizeof(struct _string)];
>
>and it will work on any platform/compiler/memory model.
> [...]
>--Joe English
>  jeenglis@alcor.usc.edu


This won't work because if you check the original article, you'll
see that his #ifdef's hide the struct _string.

#ifdef INFO_HIDING
    typedef char String[???];
#else
    typedef struct _string {
     ...
    } String;
#endif

When the compiler needs to know the array size, the struct _string isn't
visable.



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