From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org)
	by finch.gentoo.org with esmtp (Exim 4.60)
	(envelope-from <gentoo-dev+bounces-45835-garchives=archives.gentoo.org@lists.gentoo.org>)
	id 1QO6GJ-0005kG-FW
	for garchives@archives.gentoo.org; Sun, 22 May 2011 10:51:55 +0000
Received: from pigeon.gentoo.org (localhost [127.0.0.1])
	by pigeon.gentoo.org (Postfix) with SMTP id 62BFB1C01E;
	Sun, 22 May 2011 10:51:44 +0000 (UTC)
Received: from amun.cheops.ods.org (amun.cheops.ods.org [83.161.135.166])
	by pigeon.gentoo.org (Postfix) with ESMTP id E8A7D1C007
	for <gentoo-dev@lists.gentoo.org>; Sun, 22 May 2011 10:51:09 +0000 (UTC)
Received: from tefnut.cheops.ods.org ([2001:980:57a5:1:211:24ff:fe37:e46e] helo=gentoo.org)
	by amun.cheops.ods.org with esmtps (TLSv1:AES256-SHA:256)
	(Exim 4.76)
	(envelope-from <grobian@gentoo.org>)
	id 1QO6FY-0006q8-E6
	for gentoo-dev@lists.gentoo.org; Sun, 22 May 2011 12:51:09 +0200
Date: Sun, 22 May 2011 12:50:43 +0200
From: Fabian Groffen <grobian@gentoo.org>
To: gentoo-dev@lists.gentoo.org
Subject: Re: [gentoo-dev] RFC: sed script redundancy
Message-ID: <20110522105043.GO24801@gentoo.org>
Mail-Followup-To: gentoo-dev@lists.gentoo.org
References: <20110520173922.391ea292@epia.jer-c2.orkz.net>
 <20110520155600.GB24801@gentoo.org>
 <20110521193434.3f623fa6@epia.jer-c2.orkz.net>
Precedence: bulk
List-Post: <mailto:gentoo-dev@lists.gentoo.org>
List-Help: <mailto:gentoo-dev+help@lists.gentoo.org>
List-Unsubscribe: <mailto:gentoo-dev+unsubscribe@lists.gentoo.org>
List-Subscribe: <mailto:gentoo-dev+subscribe@lists.gentoo.org>
List-Id: Gentoo Linux mail <gentoo-dev.gentoo.org>
X-BeenThere: gentoo-dev@lists.gentoo.org
Reply-to: gentoo-dev@lists.gentoo.org
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20110521193434.3f623fa6@epia.jer-c2.orkz.net>
User-Agent: Mutt/1.5.21 (Darwin 8.11.0, VIM - Vi IMproved 7.3)
Organization: Gentoo Foundation, Inc.
X-Content-Scanned: by amun.cheops.ods.org (Exim Exiscan) using SpamAssassin and ClamAV
X-Archives-Salt: 
X-Archives-Hash: e865a3c5bf182a0d713de47c8e5f38c2

On 21-05-2011 19:34:34 +0200, Jeroen Roovers wrote:
> On Fri, 20 May 2011 17:56:00 +0200
> Fabian Groffen <grobian@gentoo.org> wrote:
> 
> >   sed -e "<pattern>" "${file}" | diff "${file}" -
> > 
> > followed by the actual sed -i -e ...
> > 
> > This way I didn't need to write an intermediate file.
> 
> The problem there is that sed might be called just once on any one file,
> but in the tree it is often invoked with multiple scripts, so this
> simple implementation lacks a way to evaluate which sed scripts are
> useful.
> 
> Also, how do I ensure the sed replacement works only on invocations
> inside the ebuild, and not, say, in portage's internals?

(not tested, but as proof of concept)

alias sed my_sed
my_sed() {
	local oargs="${@}"
	local arg
	local nargs=()
	local hadi=
	local hade=
	while [[ -n $1 ]] ; do
		case "$1" in
			-i)
				# ignore this flag
				hadi=yes
				;;
			-e|-f)
				shift
				nargs+=( "-e$1" )
				hade=yes
				;;
			-*)
				nargs+=( "$1" )
				hade=yes
				;;
			*)
				if [[ -z ${hade} ]] ; then
					nargs+=( "$1" )
				elif [[ -z ${hadi} ]] ; then
					# there is no inline replacing, not much we can do
					break
				else
					sed "${nargs[@]}" "$1" | diff -q "$1" - > /dev/null \
						&& ewarn "sed ${oargs} has no effect on $1" 
				fi
				;;
		esac
		shift
	done

	\sed "${oargs}"
}


-- 
Fabian Groffen
Gentoo on a different level