Re: ${prefix} expansion in configure.ac ?

[Stepan Kasal]

Hi,

On Fri, Feb 04, 2005 at 03:58:51PM +0200, Philippe Trottier wrote:
> CPPFLAGS=-I${prefix}/include
> LDFLAGS=-L${exec_prefix}/lib
> 
> Is there better way to expand ${prefix} other than using sed ?

yes, use the shell builtin `eval'.  The following macro can serve as an
example:
http://www.gnu.org/software/ac-archive/ac_define_dir.html

So you can do this in your configure.ac:

m4_define([DIR_EXISTS],
[prefix_NONE= exec_prefix_NONE=
test "x$prefix" = xNONE && prefix_NONE=yes && prefix=$ac_default_prefix
test "x$exec_prefix" = xNONE && exec_prefix_NONE=yes && exec_prefix=$prefix
eval ac_define_dir="\"$1\""
test "$prefix_NONE" && prefix=NONE
test "$exec_prefix_NONE" && exec_prefix=NONE
test -d "$ac_define_dir" dnl
])dnl

And call it as

DIR_EXISTS($includedir) && CPPFLAGS="-I$includedir $CPPFLAGS"

or

AC_MSG_CHECKING([for headers directory])
if DIR_EXISTS($includedir); then
     CPPFLAGS="-I$includedir $CPPFLAGS"
     AC_MSG_RESULT($includedir)
else
     AC_MSG_RESULT(none)
fi

I noticed several slight problems in your code:

>        enableval="yes"
...
> if test "$enableval" = "yes" ; then

You should use enable_search_prefix in both cases.
`enableval' is available only in the code given as arguments to
AC_ARG_ENABLE, and even if you set it, enable_search_prefix will
remain unset.

> AC_MSG_CHECKING([prefix for libraries and headers])
...
>     AC_MSG_RESULT([yes])

I believe you are too verbose here.  Determining the value of one variable,
moreless directly set by the user, doesn't qualify as a `check' in my eyes.

HTH,
        Stepan Kasal