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

[Stepan Kasal]

Hi,

On Mon, Feb 07, 2005 at 03:40:02PM +0200, Philippe Trottier wrote:
> 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 ?

if it's set to NONE, it means it hasn't been given on the command line.
Perhaps a macro below will execute

        test $exec_prefix = NONE

to see whether a value was given or not.  I don't want to destroy this
information, so I restore the previous state.

It would be also possible to do something like:

test "x$prefix" = xNONE &&  prefix=$ac_default_prefix
test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
eval eval ac_define_dir="\"\\\"$1\\\"\""
test -d "$ac_define_dir" dnl

or even:

test "x$prefix" = xNONE &&  prefix=$ac_default_prefix
test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
eval eval test -d "\"\\\"$1\\\"\"" dnl

But please note that I had to change the value assigned to exec_prefix,
and I had to add one more `eval' on that account.

The reason is that in the generated Makefiles, you should see:

        exec_prefix = ${prefix}

not the value of $prefix.  This subtle difference enables the following:

        make prefix=...

which should change both prefix and exec_prefix variables.

To sum up, I think the solution with restoring NONEs is the cleanest way.

Have a nice day,
        Stepan Kasal