From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: buildroot@busybox.net
Subject: [Buildroot] [PATCH] pkg-infra: use ?= instead of ifdef
Date: Mon, 19 Mar 2012 09:57:47 +0100 [thread overview]
Message-ID: <20120319095747.4b571e8f@skate> (raw)
In-Reply-To: <1332113334-20119-1-git-send-email-arnout@mind.be>
Hello,
Le Mon, 19 Mar 2012 00:28:54 +0100,
"Arnout Vandecappelle (Essensium/Mind)" <arnout@mind.be> a ?crit :
> ifdef considers a variable undefined if it is defined as empty. In the
> GENTARGETS/AUTOTARGETS/CMAKETARGETS infrastructure, the ifdef construct
> is often used to default to the value from the target-variable if the
> host-variable is not defined. However, this makes it impossible to
> override the host-variable as empty. Therefore, use ?= instead to assign
> the defaults.
Could you share a specific example on why this would be useful? I'm
sure there are uses cases, but I'm curious about the one you're having.
> I didn't touch the _VERSION infrastructure because I'm afraid to break it.
> In fact, I think it already is broken (I don't see how that /-to-_
> substitution can work for host-packages).
Not sure I understand what is broken here. What does "/-to-_" means?
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2012-03-19 8:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-18 23:28 [Buildroot] [PATCH] pkg-infra: use ?= instead of ifdef Arnout Vandecappelle
2012-03-19 8:57 ` Thomas Petazzoni [this message]
2012-03-19 21:51 ` Arnout Vandecappelle
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