[CMake] configure_file without continuous re-build

[Daniel Blezek]

We have a large-ish system.  Deep within an included utility class, I have
this code:

CONFIGURE_FILE(${DCMTK_SOURCE_DIR}/osconfig.h.in
               ${DCMTK_BINARY_DIR}/include/dcmtk/config/osconfig.h)

However, every time I touch a CMake file, ³osconfig.h² is regenerated,
causing nearly the entire library to re-build because of dependancies.  Is
this a good/proper/recommended way to guard against regeneration of the
file?

# NB: you would need to delete the configured osconfig.h to re-generate.
if ( NOT EXISTS ${DCMTK_BINARY_DIR}/include/dcmtk/config/osconfig.h)
message ( STATUS "Reconfigure" )
CONFIGURE_FILE(${DCMTK_SOURCE_DIR}/osconfig.h.in
               ${DCMTK_BINARY_DIR}/include/dcmtk/config/osconfig.h)
endif()


Or is there some little known, little documented CMake feature that I don¹t
know about?

Thanks,
-dan

-- 
Daniel Blezek, PhD
Medical Imaging Informatics Innovation Center

P 127 or (77) 8 8886
T 507 538 8886
E blezek.daniel at mayo.edu

Mayo Clinic
200 First St. S.W.
Harwick SL-44
Rochester, MN 55905
mayoclinic.org


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