[CMake] How to regenerate source file during make?

[David Cole]

On Fri, Jan 15, 2010 at 10:25 AM, Marcel Loose <loose at astron.nl> wrote:

> On Fri, 2010-01-15 at 10:07 -0500, David Cole wrote:
> > On Fri, Jan 15, 2010 at 9:44 AM, Marcel Loose <loose at astron.nl> wrote:
> >         Hi Jack,
> >
> >         The difference with your and my case is that you have an input
> >         file
> >         (the .xsd file) and output files (the .h and .cpp files). In
> >         my case I
> >         generate the output file, e.g. myheader.h, from myheader.h.in,
> >         using
> >         configure_file(). The problem is that I cannot get this to
> >         work during
> >         'make', only during 'cmake'.
> >
> >         Best regards,
> >         Marcel Loose.
> >
> >         On Fri, 2010-01-15 at 15:04 +0100, Smith Jack (Ext. - UGIS -
> >         UniCredit
> >
> >         Group) wrote:
> >         > I do a similar thing with an XSD file from which I generate
> >         c++
> >         wrapper classes for accessing the corresponding XML
> >         >
> >         > Note the DEPENDS line !
> >         >
> >         > MACRO(XSD FILE NAMESPACE)
> >         >     ADD_CUSTOM_COMMAND(
> >         >         OUTPUT  ${CMAKE_CURRENT_SOURCE_DIR}/xml/${FILE}.cpp
> >         >         OUTPUT  ${CMAKE_CURRENT_SOURCE_DIR}/xml/${FILE}.h
> >         >         DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/xml/${FILE}.xsd
> >         >         COMMAND ${XAPI_CODESYNTH}/bin/xsd
> >         >         ARGS cxx-tree --generate-serialization
> >         --hxx-suffix .h
> >         --cxx-suffix .cpp --fwd-suffix -fwd.hxx --type-naming java
> >         --function-naming java --namespace-map =${NAMESPACE}
> >         --generate-polymorphic --output-dir
> >         ${CMAKE_CURRENT_SOURCE_DIR}/xml
> >         ${CMAKE_CURRENT_SOURCE_DIR}/xml/${FILE}.xsd
> >         >         COMMENT "generating Codesynthesis Wrappers")
> >         > ENDMACRO(XSD)
> >         >
> >         >
> >         >
> >         > > -----Original Message-----
> >         > > From: cmake-bounces at cmake.org
> >         > > [mailto:cmake-bounces at cmake.org] On Behalf Of Marcel Loose
> >         > > Sent: Friday, January 15, 2010 2:55 PM
> >         > > To: cmake at cmake.org
> >         > > Subject: [CMake] How to regenerate source file during
> >         make?
> >         > >
> >         > > Hi all,
> >         > >
> >         > > I've been struggling with this for hours now and I can't
> >         seem
> >         > > to get a grip on it.
> >         > >
> >         > > I have a header file that must be (re)generated during
> >         'make'
> >         > > when some external data have changed. I can successfully
> >         > > generate this file during 'cmake' using configure_file(),
> >         but
> >         > > I haven't been able to figure out how I can trigger the
> >         > > configure_file() during make.
> >         > >
> >         > > Should I define a target for this header file? Or can I
> >         > > specify some kind of file dependency, such that when the
> >         > > header file is missing our out-of-date, it will be
> >         (re)generated?
> >         > >
> >         > > I guess it must be some clever combination of
> >         > > add_custom_command() and add_custom_target().
> >         > >
> >         > > Best regards,
> >         > > Marcel Loose.
> >
> >
> >
> > This should work already: if you change my_header.h.in then cmake
> > should re-run to re-configure your file at 'make' time.
> >
> >
> > If you have additional dependencies that should trigger a
> > re-configure, you should probably convert it to an add_custom_command
> > such that it happens at build time.
>
> It's not the myheader.h.in that's changing; myheader.h should be
> regenerated because the value of one of the variables in myheader.h.in
> (that get expanded) change.
>
> To be more precise, I try to record the svn revision number (and some
> more svn info). I carefully read
> http://www.mail-archive.com/cmake@cmake.org/msg25922.html, because it
> closely matches my problem, but I couldn't figure out what
> update_version.cmake should do exactly. In my case, I would need the
> values of a number CMake variables (like CMAKE_CURRENT_BINARY_DIR), but
> of course, these values are not around anymore when running 'make'.
> Should all these variables be passed using -D?
>
>
Yes. Put the configure_file call into a cmake -P script. Then use
add_custom_command to call it, passing all the variables required with -D
args before the -P arg.

Sounds like you'll need to run svn status and svn info *always* and then run
this command afterwards *if* something is different than last time it ran...

HTH,
David
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