Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!mailrus!uflorida!gatech!cumulus!hsu
From: hsu@cumulus (Yung-Kao Hsu)
Newsgroups: comp.lang.c++
Subject: Re: Can we hide the private part of a class ?
Summary: programmers want to but can't
Keywords: header dependency, efficiency.
Message-ID: <1375@cumulus>
Date: 3 Oct 88 15:52:02 GMT
References: <1358@stratus* <1988Sep29.044111.16104@utzoo.uucp> <4223@polya.Stanford.EDU>
Organization: Georgia Institute of Technology
Lines: 36


In article <4223@polya.Stanford.EDU* shap@polya.Stanford.EDU
(Jonathan S. Shapiro) writes:

*In article <1368@cumulus> hsu@cumulus.UUCP (Yung-Kao Hsu) writes:
**
**In article <1988Sep29.044111.16104@utzoo.uucp* henry@utzoo.uucp
**(Henry Spencer) writes:
**
***The user can't access x, so seeing it won't do him much good.  However,
**
**This is true if all public functions won't return any pointer to x.
**But, sometimes for efficiency reason, we will allow such bad pratice.
*
*The fact that a programmer can willfully break the type system is not
*a good argument here. I can also use integer pointers as character
*pointers. If the function returning pointer wants to be type-safe,
*it should be declared as returning a pointer to a class member. In
*that case, what Henry says continues to be true.
*
*Jon

What I really should say in the previous posting is: the language should
provide some mechanisms (i.e, hiding the data type definition) that prevent
the programmer from mis-use even they want to.

Also, your example is not quite convincing, since character and integer
are not considered as "private" types but pre-defined public data types
and we all know how they are implemented.

-----
-- 
YUNG-KAO HSU
School Of Infomation & Computer Science, Georgia Tech Atlanta GA30332
Internet:  hsu@cumulus.gatech.edu	 CSNet:  hsu%cumulus@gatech	
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