On Mon, 2007-04-09 at 16:20 -0700, Ben Wilhelm wrote:
> a b c d: source.flag
> @true
>
> source.flag: source
> ( touch source.flag && blackbox_generate a b c d ) \
> || ( rm -f source.flag && false ) # eugh
>
> but this is horribly ugly, although it does work. (I think the @true is
> necessary but to be honest I'm hazy as to why, although it doesn't
> rebuild the things that depend on a b c d without it.)
You can write this much more cleanly, like this:
a b c d: .source_flag
@:
.source_flag: source
blackbox_generate a b c d
@touch .source_flag
> Is there a good solution to this? Ideally one without extra temporary
> files? While I know why the first case doesn't work ("A rule with
> multiple targets is equivalent to writing many rules, each with one
> target, and all identical aside from that." from 4.10 in the make
> manual) I haven't been able to figure out how to get the behavior I want.
There are only two ways to do what you want. The one above works for
all types of targets.
The other way is to use pattern rules: if your targets and a
prerequisite share a stem that can be matched by a pattern ("%"), then
you can write:
%a %b %c %d: %source
blackbox_generate $*a $*b $*c $*d
Unlike explicit rules, pattern rules with multiple targets behave as you
are looking for: they build all the targets with one invocation of the
command script.
If you can't use pattern rules then you must use temporary files, sorry.
Although the method I show above is much cleaner, and users will
probably not notice the difference.
--
-------------------------------------------------------------------------------
Paul D. Smith <[EMAIL PROTECTED]> Find some GNU make tips at:
http://www.gnu.org http://make.paulandlesley.org
"Please remain calm...I may be mad, but I am a professional." --Mad Scientist
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