NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/gnu/misc/discuss/4080

Text File | 1992-12-22 | 1.5 KB | 43 lines

Newsgroups: gnu.misc.discuss
Path: sparky!uunet!think.com!ames!agate!spool.mu.edu!umn.edu!news
From: [e-mail] (Linus Upson)
Subject: #import
Message-ID: <[e-mail]>
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Organization: University of Minnesota
Date: Mon, 21 Dec 1992 21:12:26 GMT
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I just finished installing gcc 2.3.2 on the Irises here (Objective-C
works!), and on my first compile was greeted with the following message:

% gcc ttt.m -lobjc
ttt.m:1: warning: using `#import' is not recommended
The fact that a certain header file need not be processed more than once
should be indicated in the header file, not where it is used.
The best way to do this is with a conditional of this form:

  #ifndef _FOO_H_INCLUDED
  #define _FOO_H_INCLUDED
  ... <real contents of file> ...
  #endif /* Not _FOO_H_INCLUDED */

Then users can use `#include' any number of times.
GNU C automatically avoids processing the file more than once
when it is equipped with such a conditional.

A person here pointed me to -Wno-import, but I was wondering if someone
could answer a couple of questions for me:
1. Why is this warning on by default?  It seems that import allows greater
flexibility on the part of the programmer using the header.
2. How can I turn it off permanently?  The only way I came up with was to
modify the source.

I realize that this topic is probably extremely flammable, so please reply
to me via email.

Linus Upson
The Geometry Center
[e-mail]