Calling SED for a source in Makefile.am

Question

I've got c++ code that needs a sed done to it prior to compilation. How do I place this into Makefile.am?

I tried the typical makefile setup and the target appears to not exist:

gentest.cc:

$(SED) -i "s|FIND|REPLACE|" gentest.cc

If you are interested as to why I want to do this, it's because I wrote my program (slider3.py) in python and my partner wrote his in c++ (gentest.cc) and his needs to call mine. I'm accomplishing this by editing the argv and then using execv().

... {

char **argv2 = new char*[argc];

memset(argv2,0,sizeof(argv2));

argv2[0] = "__PREFIX__/bin/slider3.py";

memcpy(argv2 + 1, argv + 2, sizeof(char *) * (argc - 2));

int oranges = execv(argv2[0], argv2);

printf("%s\n", strerror(oranges));

return oranges;

} ...

I've already handled getting the #! added to slider3.py and chmod +x by using the method that was not working for gentest.cc. I've also handled adding slider3.py to the list of files that get installed.

EXTRA_DIST=testite.sh slider3_base.py

bin_SCRIPTS = slider3.py

CLEANFILES = $(bin_SCRIPTS)

slider3.py: slider3_base.py

rm -f slider3.py

echo "#! " $(PYTHON) > slider3.py

cat slider3_base.py >> slider3.py

chmod +x slider3.py

gentest is defined this way in Makefile.am:

bin_PROGRAMS = gentest

gentest_SOURCES = gentest.cc

gentest_LDADD = libgen.a #../libsbsat.la $(LIBM)

And this fails to be run during make (note the @ pattern is successfully expanded in Makefile):

gentest.cc:

$(SED) -i "s|__PREFIX__|@prefix@|" gentest.cc

Any ideas on how to get sed to run before compiling gentest.cc?

Answer 1

Don't use in-place sed.

Instead:

gentest_SOURCES = gentest-seded.cc

gentest-seded.cc : gentest.cc
    $(SED) "s|__PREFIX__|@prefix@|" $< >$@

Answer 2

Have you ever considered #define-ing it in config.h (you're using autotools, right?) or passing it using -D when compiling? This is really not the case for sed.

The details from Andrew Y's answer:

in your C++ source, specify:

argv2[0] = SCRIPTPREFIX "/bin/slider3.py";

then compile with

-DSCRIPTPREFIX='"/your/script/prefix"'

Answer 3

Have you considered calling the Python code directly from the C++? Here is a tutorial on using boost to call python functions from C++. The method you are describing here seems very brittle.