Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!hao!gatech!mcnc!rutgers!bellcore!faline!ulysses!mhuxt!m10ux!rgr
From: rgr@m10ux.UUCP (Duke Robillard)
Newsgroups: comp.lang.c
Subject: Re: A bad design decision early on in A
Message-ID: <472@m10ux.UUCP>
Date: 4 Jan 88 18:08:22 GMT
References: <1322@sugar.UUCP> <47000028@uxe.cso.uiuc.edu>
Reply-To: rgr@m10ux.UUCP (Duke Robillard)
Organization: AT&T Bell Labs, Murray Hill
Lines: 26

In article <47000028@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>>	But they do - they add data hiding.  A library can provide
>>	types such as time_t and addr_t for data that is generated by
>>	some library routines and used by others, and *you* don't have
>>	to know what the type is.  If the variable won't fit in a
>Data hiding is the worst idea ever invented. I really hate it when I find
>something declared as a "time_t", or , worse, those awful structures
>used by VMS C for system calls. Then one has to go back through some long
>chain of garbage to find what they really mean. 

This is because you're not really hiding the data.  You still have to 
know what time_t is to use the information.  I hate this too.  Pascal's
types can lead to a viciously unreadable program by their misuse.

But with a *real* implementation of data hiding, you wouldn't have to
go back through that long chain of garbage.  To set some variable of
type foo, you'd call a function called set_foo.  To print the time,
you'd call a routine called print_time_t.  This is a major concept 
behind "object oriented programming" languages, like smalltalk or (maybe)
C++.



-- 
+                                
|               Duke Robillard, novice pagan. 
|       AT&T Bell Labs           m10ux!rgr@ihnp4.UUCP                 
|       Murray Hill, NJ          {any biggy}!ihnp4!m10ux!rgr