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

[Philippe Trottier]

Stepan Kasal wrote:

> 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 ?
> >    
here is something I have noticed, exec_prefix is set to NONE until the 
end of the config script... now I am thinking to see if it is set at 
NONE and if it is then set exec_prefix to ${prefix}, and put it back to 
NONE afterward ... does that make any sense ?

> 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.
>  
Ok good, for later trouble finding ---

> > 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.
>  
I am more or less trying to find the evil in this, so I got really 
verbose...

Thank you very much for the help here !

Philippe