Newsgroups: comp.lang.c++
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: #once cpp directive implemented!
Message-ID: <1989Mar21.215138.6881@utzoo.uucp>
Organization: U of Toronto Zoology
References: <124@riunite.ACA.MCC.COM>
Date: Tue, 21 Mar 89 21:51:38 GMT

In article <124@riunite.ACA.MCC.COM> rfg@riunite.UUCP (Ron Guilmette) writes:
>... patches for the the GNU C
>preprocessor (version 1.34) which implement the new #once
>directive...
>The semantics of the #once directive are simple.  The #once
>directive causes any file it appears in to be included no more
>than one time during any given individual compilation...

Was it really necessary to invent a new directive for this?  The existing
construct:

	#ifndef gorble_h
	#define	gorble_h 1
	...
	#endif

suffices.  Patches to the compiler to recognize *this* construct in an
include file, and optimize out future references to that file, would
do the same job and be 100% compatible with both existing practice
and existing standardization efforts.  #once is neither.
-- 
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