Standard AC macro calls

[Erickson, David]

I'm curious why the macros

AC_CONFIG_SUBDIRS
and
AC_SUBST

take differing arguments to work?

In this snippet

# find all subdirectories that will have source code and therefore libraries.
# add the subdirs for configuration and the libary to the superlibrary
for FILE in `ls -d */`
do
    case "$FILE" in
        autom4te* ) continue ;; #
        m4*)         continue ;; #
        * )
        SRC_SUBDIRS+=" $FILE"
        LIB_LIBSRC+="lib${FILE:0:-1}.la "
    esac
done
AC_CONFIG_SUBDIRS([${SRC_SUBDIRS}])
AC_SUBST(SRC_SUBDIRS)

I could get them both to work but only in these differing ways. Trust me, I 
tried them all.

Can someone please explain -  succinctly - why this is so?

Thanks,
Dave

D.R. Erickson
Defence Research and Development Canada Suffield | Recherche et développement 
pour la défense Canada Suffield
Medicine Hat, AB, Canada T1A 8K6
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