Autoconf, automake and friends

An Example Macro

Macros are not trivial to write, since they need to extract their information without interfering with the external system. They also need to account for many possibilities.

AC_DEFUN([JH_PYTHON_CHECK],
[AC_CACHE_VAL([jh_cv_path_python],
[if test "x$PYTHON" != x; then
  jh_cv_path_python="$PYTHON"
else
    dnl python code to check for required python
    jh_python_check='
    import sys, string
    if sys.version_info < $1:
        sys.exit(1)
    $2
    sys.exit(0)'
    dnl
    
      for jh_python in python python2 python2.3 python2.2 python2.1 python2.0;
      do
        jh_save_IFS=$IFS; IFS=$PATH_SEPARATOR
        jh_dummy="$PATH"
        for jh_dir in $jh_dummy; do
    ...
        done
        test -n "$jh_cv_path_python" && break
      done
fi
])