Listing 2

dnl
dnl MYPROJECT_ENABLE_PROFILING
dnl
dnl sets output variables to be used as 
dnl compiler flags related to profiling, e.g.
dnl with GNU gprof.
dnl
dnl Sets outcatput variable: @CXXFLAG_PROFILING@
dnl

AC_DEFUN(
[MYPROJECT_ENABLE_PROFILING],
[
AC_ARG_ENABLE(
    [profiling],
    AC_HELP_STRING([--enable-profiling], [build executables for profiling]),
    [
        AC_MSG_NOTICE([Enabling runtime profiling flags])
        AC_SUBST(CXXFLAG_PROFILING, ["-pg"])
    ],
    [
        ## no need to send a message if we're not profiling
        AC_SUBST(CXXFLAG_PROFILING, [""])
    ]
)
]
)