[CMake] macro within a custom command

[Brandon J. Van Every]

What I really want is a simple text substitution macro, of the form:

MACRO(SIMPLE_SCM_TO_C root)
  ${VALID_CHICKEN} ${Chicken_SOURCE_DIR}/${root}.scm -output-file 
${Chicken_BINARY_DIR}/${root}.c ${CHICKEN_FLAGS})
ENDMACRO(SIMPLE_SCM_TO_C)

and then put this inside of a custom command so I don't have to type the 
same boring thing for every single custom command.

ADD_CUSTOM_COMMAND(
  OUTPUT ${Chicken_BINARY_DIR}/batch-driver.c
  MAIN_DEPENDENCY batch-driver.scm
  DEPENDS parameters.scm
  COMMAND SIMPLE_SCM_TO_C(batch-driver)
)

But MACRO doesn't actually work that way.  It insists on being 
constructed out of commands.  So I write:

MACRO(SIMPLE_SCM_TO_C root)
  EXECUTE_PROCESS(${VALID_CHICKEN} ${Chicken_SOURCE_DIR}/${root}.scm 
-output-file ${Chicken_BINARY_DIR}/${root}.c ${CHICKEN_FLAGS})
ENDMACRO(SIMPLE_SCM_TO_C)

I try to use it in the ADD_CUSTOM_COMMAND as above, but on the line 
containing COMMAND, I get, <<Parse error. Function missing ending ")".  
Instead found left paren with text "(".>>  As far as I can tell, nothing 
is actually mismatched.  Rather, it appears that a MACRO simply cannot 
be used on a COMMAND line.

If there's no way to perform a simple text substitution on a custom 
build rule's COMMAND line, then that's really really irritating.  I 
already had to expand out all my build rules into explicit 
ADD_CUSTOM_COMMAND statements, because only DEPENDS works on 
source-file-to-source-file dependencies.  ADD_FILE_DEPENDENCIES is 
useless for that purpose.  So I wanted to use a text macro to preserve 
what little is left of my sanity, so that I don't have to cut 'n' paste 
the same stupid rules 100 times, and have people make gratuitous 
mistakes over time with 'em.


Cheers,
Brandon Van Every