> Hi Steven, > > If I remember correctly a changed value in "-D flag" will not cause > re-compilation, so if it is important that the version information > propagates to your binary, it is likely better to generate a header file or > even a source file than using these CPPFLAGS. I'm doing that in one of my > projects in which the makefile.am looks something like this > > if HAVE_SVN_WC > @srcdir@/subversion_info.cc: subversion_info.cc.tmp > @$(SHELL) @top_srcdir@/build_support/move-if-change subversion_info.cc.tmp > \ > @srcdir@/subversion_info.cc > > subversion_info.cc.tmp: FORCE > @echo '// subversion_info.cc generated from subversion_info.cc.in.' > $@ > ;\ > revision=`svnversion $(top_srcdir)` ;\ > $(SED) -e 's/sub_2_svn_revision/'$$revision'/g' \ > @srcdir@/subversion_info.cc.in >> $@ ; > endif > > FORCE: > > Then I have a subversion_info.cc.in that have a string sub_2_svn_revision > where the revision is intended to be. So when I need `subversion_info.cc', a > `subversion_info.cc.tmp' is created from the `subversion_info.cc.in' using > the handy script, svnversion, provided by the svn team. Then the script > move-if-change replaces `subversion_info.cc' with `subversion_info.cc.tmp' > (like mv subversion_info_cc.tmp subversion_info.cc) but it does so only if > the two files are different. I introduced that "if" in order to avoid > re-compilation of subversion_info.o when not needed. > > Another thing is that if you plan on distributing your package, you have to > make sure that it works also when not building from a subversion working > copy. Either by adding this case in your script `svnrev-sh' or by checking > it at configure time and add automake conditionals (like I do with > HAVE_SVN_WC). In any case you probably need to add created source code > `subversion_info.cc' to your distribution. I used `make distcheck' to help > me get the details right. > > I am not sure exactly what you wanna do, but I hope this will help. >
Thank you Peter. I have two more questions: 1, Where and how you set the HAVE_SVN_WC? 2. What's the difference between @varname@ and $(varname) in a Makefile.am? I noted you use many @xxxx@ Regards, woody
