autoconf: Cache Checkpointing

1 
1 7.4.3 Cache Checkpointing
1 -------------------------
1 
1 If your configure script, or a macro called from `configure.ac', happens
1 to abort the configure process, it may be useful to checkpoint the cache
1 a few times at key points using `AC_CACHE_SAVE'.  Doing so reduces the
1 amount of time it takes to rerun the configure script with (hopefully)
1 the error that caused the previous abort corrected.
1 
1  -- Macro: AC_CACHE_LOAD
1      Loads values from existing cache file, or creates a new cache file
1      if a cache file is not found.  Called automatically from `AC_INIT'.
1 
1  -- Macro: AC_CACHE_SAVE
1      Flushes all cached values to the cache file.  Called automatically
1      from `AC_OUTPUT', but it can be quite useful to call
1      `AC_CACHE_SAVE' at key points in `configure.ac'.
1 
1    For instance:
1 
1       ... AC_INIT, etc. ...
1      # Checks for programs.
1      AC_PROG_CC
1      AC_PROG_AWK
1       ... more program checks ...
1      AC_CACHE_SAVE
1 
1      # Checks for libraries.
1      AC_CHECK_LIB([nsl], [gethostbyname])
1      AC_CHECK_LIB([socket], [connect])
1       ... more lib checks ...
1      AC_CACHE_SAVE
1 
1      # Might abort...
1      AM_PATH_GTK([1.0.2], [], [AC_MSG_ERROR([GTK not in path])])
1      AM_PATH_GTKMM([0.9.5], [], [AC_MSG_ERROR([GTK not in path])])
1       ... AC_OUTPUT, etc. ...
1