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Date: Thu, 19 Jun 2008 12:21:08 +0200
From: Pietro Cerutti <gahr@FreeBSD.org>
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To: Kris Kennaway <kris@FreeBSD.org>
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Cc: ports@FreeBSD.org
Subject: Re: INDEX build optimizations - please review
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Kris Kennaway wrote:

| **********************************************************************
| ********************* NOTE TO PORT DEVELOPERS ************************
| **********************************************************************
|
| Variable assignments with != are bad!  Try as hard as you can to avoid
| using them -- especially in Mk/*!  Every time something processes your
| makefile it will spawn a command, even if it is not relevant for the
| operation being performed.  If you need to run shell commands, try to
| isolate them within a makefile target.  You can avoid code duplication
| by assigning the *shell commands* (not their output) to a variable and
| inserting it into your code block.
|
| e.g. instead of
|
| --
| VARIABLE!=    do some shell stuff; do some other stuff
|
| target:
|     echo ${VARIABLE}
| --
|
| do this (or similar):
|
| --
| VARIABLE_CMDS=    do some shell stuff; do some other stuff
|
| target:
|     echo $(${VARIABLE_CMDS})
| --
|
| This defers the command execution to the point where the target runs, so
| in the case when the target is *not* run, then you avoid wasting one or
| more process executions.

Yes, in theory.

Any clue why this doesn't work?

SCHED_NAME=     sysctl -n kern.sched.name

all:
~        echo $(${SCHED_NAME})

|
| Kris
|


- --
Pietro Cerutti
gahr@FreeBSD.org

PGP Public Key:
http://gahr.ch/pgp

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