On 08.03.12 09:50:55, Michael Jackson wrote:
> On Mar 7, 2012, at 11:43 AM, Andreas Pakulat wrote:
>
> > On 07.03.12 10:10:27, Michael Jackson wrote:
> >> In an effort to speed up the build of a project that uses Qt (and moc) I
> >> tried an alternate approach with the moc files. Normally I use the basic
> >> idea of gathering the headers that need to be "moc'ed" and feed those to
> >> moc with this type of CMake Code:
> >>
> >> QT4_WRAP_CPP( FilterWidgets_Generated_MOC_SRCS ${QFilterWidget_HDRS}
> >> ${FilterWidget_GEN_HDRS})
> >>
> >> The in the Add_Executable(...) call include the
> >> ${FilterWidgets_Generated_MOC_SRCS} variable to the list of sources. In my
> >> project I have at least 30 auto-generated files which all get moc'ed. That
> >> gives me an additional 60 compiled files. So I tried the idea of #include
> >> "moc_[some_file.cxx]" in each of the auto-generated .cpp files for each
> >> Widget. This would cut the number of files compiled in half. The issue is
> >> that since they are being #include'ed in the .cpp files then they do NOT
> >> need to be compiled themselves so I took the
> >> ${FilterWidgets_Generated_MOC_SRCS} out of the list of sources in the
> >> add_executable() call. What happened is that CMake did NOT run moc on
> >> those headers because there were now NOT included in the build.
> >>
> >> So for that version of the cmake code I have something like this:
> >>
> >> QT4_WRAP_CPP( FilterWidgets_Generated_MOC_SRCS ${FilterWidget_GEN_HDRS})
> >> QT4_WRAP_CPP( FilterWidgets_MOC_SRCS ${QFilterWidget_HDRS} )
> >>
> >> Is there a way to forcibly run the moc step even if the resulting source
> >> files are NOT directly included in the add_executable? Custom_Command?
> >> Add_Depends?
> >
> > A few options I can think of:
> >
> > - Use the automoc developed as part of KDE (its pure-Qt though)
> > https://projects.kde.org/projects/kdesupport/automoc/repository
> > - Use the automoc function from FindQt4.cmake
> > - Use the new automoc function in CMake 2.8.7
> >
> > All of these will help handle the qt4_wrap_cpp stuff for you as long as
> > you have the #include. Note that I think there's at least 2 or 3
> > differnet filenames for the include depending on which of the above you
> > use (foo.moc vs moc_foo.cpp vs. moc_foo.cxx or something like that).
> >
> > If none of them is an option for you then I guess using
> > add_custom_target and add_dependencies is the way to go.
> >
> > Andreas
> >
> I looked into the automoc functionality and after some tinkering around I
> think there is still a disconnect in my cmake code. When are the
> source/header files scanned by automoc to determine if they will have moc run
> on them.
> Currently during cmake time I generate a blank header and source file
> (well, there is a #error ... in them) which then get over written by a new
> files during build time. The new files are complete and proper C++ source
> files/headers with the Q_OBJECT macro in the header and #include "moc_*.cpp"
> in the source file. When I compile (using makefiles on OS X currently as a
> test) I get an error that the moc_*.cpp file can not be found and searching
> the entire build directory does not reveal the file. If I run CMake again and
> compile then the auto moc files do appear. From this I think that automoc
> runs during CMake time. Is this correct?
Yes, all three automoc's do the header-check during cmake-time. But if
you already generate the source files during build-time couldn't you add
another step for running moc there?
Andreas
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