@node ax_numeric_namedlevel
@unnumberedsec ax_numeric_namedlevel

@majorheading Synopsis

@smallexample
AX_NUMERIC_NAMEDLEVEL(VARNAME [,FROMVAR [,DEFAULT [,YESLEVEL]]])
@end smallexample

@majorheading Description

The levelstring FROMVAR is expanded and checked for verbal names that
will map on to eight different levels - the VARNAME will receive this
numeric level where "all" maps to 7 (lower three bits set) higher levels
for 8 and 9 exist too. This macro is a nice helper to convert user input
of a --with-opt=level into a numeric form that can be simply pushed as a
#define like with AC_DEFINE:

@smallexample
 default YESLEVEL = 2 /* including unknown levelspec */
 default DEFAULT  = 0 /* when named level is empty */
 default FROMVAR  = VARNAME
@end smallexample

The DEFAULT value is used if the NAMED levelstring has become empty and
it is copied without further conversion - a default of "0" is used if
absent - identical to "no". A "yes" will be set to the YESLEVEL - and
note that "yes" has "2" as its default value not "1". (which comes from
its original use to set a "gcc -O2").

the mnemonic names are:

@smallexample
  9| insane |ultrasome|experimentalplus
  8| ultra  |ultra|experimental)
  7| all    |muchmore|somemanymore|manymoreplus
  6| most   |manymore|most)
  5| strict |somemore|almost
  4| more   |more
  3| extra  |manyplus|plusmuch|somemany|plusmany
  2| many   |many|much|(yes)
  1| some   |some|plus
@end smallexample

note that a level can be constructed of (some|plus) = bit-0, (many|much)
= bit-1, (more) = bit-2, (ultra|experimental) = bit-3 at least in a
left-to-right order, ie. plusmanymore=7

Example usage:

@smallexample
  AX_NUMERIC_NAMEDLEVEL(OPTLEVEL,with_optlevel,1,3)
  AC_DEFINE(OPTLEVEL)
  test "$GCC" = "yes" && CFLAGS="$CFLAGS -O$OPTLEVEL)
@end smallexample

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_numeric_namedlevel.m4,latest
version of @file{ax_numeric_namedlevel.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_numeric_namedlevel.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2008 Guido U. Draheim @email{guidod@@gmx.de}}

Copying and distribution of this file, with or without modification, are
permitted in any medium without royalty provided the copyright notice
and this notice are preserved.  This file is offered as-is, without any
warranty.