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Re: pattern rule dependency question
From: |
Paul D. Smith |
Subject: |
Re: pattern rule dependency question |
Date: |
Mon, 7 Mar 2005 15:54:20 -0500 |
%% Der Herr Hofrat <address@hidden> writes:
dhh> _%: $*
This rule doesn't mean anything. The automatic variables, like $@, $*,
etc. are not set in prerequisite lists; they are ONLY available inside
command scripts. So, $* is the global variable "*", which is almost
certainly not set, and this rule basically just says:
_%:
Which is pretty meaningless.
Second, a pattern rule without a command script does not define
prerequisites as an explicit rule would; instead it deletes the pattern
rule. Since there is no pattern for _%, this deletes something that
didn't exist and so doesn't do anything.
dhh> And we then call make as make _video.mss which as I had expected
dhh> then runs the %.mss rule.
Yes, because _video.mss matches that pattern, but $* here will be
"_video", not "video".
dhh> but I could not find any note in the info pages stating that
dhh> automatic variables can't be used in prerequisites
They can't be.
--
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Paul D. Smith <address@hidden> Find some GNU make tips at:
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"Please remain calm...I may be mad, but I am a professional." --Mad Scientist