Re: a small question about subst

[Paul D. Smith]

%% Ken Smith <address@hidden> writes:

  ks> Without seeing your code, I can only assume that you are trying to
  ks> do this in the command section of a rule.  If that is the case,
  ks> you'll need to use sed or something similar.

Not true.

  ks> The GNU make functions will be processed when the files are read
  ks> and not when the targets are run.

No.  Only parts of the makefile which are processed "immediately" are
processed when the files are read in.  It has nothing to do with what
KIND of thing it is (variables, functions, etc.) and everything to do
with WHERE in the makefile it appears.

The section "How make Reads a Makefile" in the manual explains which
parts of the makefile are expanded immediately, and which are deferred.

The contents of the command scripts are always deferred.

  ks> my_root=root

  ks> file1.out: $(my_root)/folder1/file1
  ks>         @echo "modified prerequisite=\"`echo $< | sed -e 
's/folder1\///'`\""

This is way overkill; a simple:

   file1.out: $(my_root)/folder1/file1
           @echo 'modified prerequisite="$(subst folder1/,,$<)"'

will work fine.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <address@hidden>          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