Hi Ralf, thanks for your reply On Mon, Sep 7, 2009 at 4:59 PM, Ralf Wildenhues <Ralf.Wildenhues@xxxxxx> wrote: > * Sam Steingold wrote on Wed, Sep 02, 2009 at 07:51:20PM CEST: >> does the cache variable name matter? >> e.g., ac_cv_have_readline is not declared cached in >> http://clisp.cvs.sourceforge.net/*checkout*/clisp/clisp/src/m4/readline.m4 >> but I do see it in config.cache. > > Generally, configure currently saves all variables matching *_cv_* > (glob notation), and considers a variable cached also if its value > is empty. It uses AS_VAR_TEST_SET to test if the variable is cached. > Being very precise, we don't document that you can use cache variables > without one of the AC_CACHE_{CHECK,VAL} macros, but I'm not sure whether > a future Autoconf version may make this a requirement. this pretty much leaves the issue moot: if you have this (undocumented) feature and people rely on it, getting rid of it would be hard. >> specifically: >> >> AC_DEFUN([AC_FOO],[dnl >> AC_ARG_WITH([foo], >> AC_HELP_STRING([--with-foo],[use this FOO installation]), >> [ac_cv_use_foo="$withval"], [ac_cv_use_foo=default]) > > By overwriting the cache variable with the value obtained from > --with-foo, you cannot tell any more whether the variable was cached > or you just read a command line argument. then, I guess, I do not want it cached. >> ac_cv_have_foo=no > > Here you just overwrite the value obtained above again. > >> if test "$ac_cv_use_foo" = "no"; > > This will then always be true. why?! I set "_have_" to "no", and I am testing "_use_" here! >> I want all the ac_cv_* vars to be cached. >> how do I arrange for that? >> i.e., should I put the "if $ac_cv_foo_command bar;" inside AC_CACHE_CHECK? >> would those _nested_ AC_CACHE_CHECKs work? > > You should have one > AC_CACHE_CHECK(MESSAGE, CACHE-ID, COMMANDS) > > or one > AC_CACHE_VAL(CACHE-ID, COMMANDS) > > for one of the CACHE-IDs. The important thing is that you don't set > that CACHE-ID outside of COMMANDS, and the COMMANDS should only set the > CACHE-ID (and the other, dependent ones, I guess). yes, this is what the manual says. alas, it does not answer my question. let me try again. I am testing for a presence of a clisp installation, please see http://clisp.cvs.sourceforge.net/*checkout*/clisp/clisp/src/m4/clisp.m4 (BTW, any critique is welcome!). what I do is: cl_cv_have_clisp=no if cl_cv_use_clisp = yes; then check_for_THIS if cl_cv_have_THIS = yes; then check_for_THAT if cl_cv_have_THAT = yes; then cl_cv_have_clisp=yes fi fi fi here is the question: where do I put AC_CACHE_VAL? around the whole top "if cl_cv_use_clisp"? or in the innermost "if cl_cv_have_THAT"? thanks. -- Sam Steingold <http://sds.podval.org> _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf
