I tried to summarize the answers to this *very* FAQ. If people see
other things to put in the FAQ, please...
Index: ChangeLog
from Akim Demaille <[EMAIL PROTECTED]>
* doc/autoconf.texi (Questions): Rename as...
(FAQ): this.
(Defining Directories): New.
Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.670
diff -u -u -r1.670 autoconf.texi
--- doc/autoconf.texi 9 Sep 2002 16:27:02 -0000 1.670
+++ doc/autoconf.texi 11 Sep 2002 10:10:28 -0000
@@ -163,7 +163,7 @@
* config.status Invocation:: Recreating a configuration
* Obsolete Constructs:: Kept for backward compatibility
* Using Autotest:: Creating portable test suites
-* Questions:: Questions about Autoconf, with answers
+* FAQ:: Frequent Questions about Autoconf, with answers
* History:: History of Autoconf
* Copying This Manual:: How to make copies of this manual
* Indices:: Indices of symbols, concepts, etc.
@@ -426,12 +426,13 @@
* testsuite Scripts:: The concepts of Autotest
* Autotest Logs:: Their contents
-Questions About Autoconf
+Frequently Asked Questions About Autoconf
* Distributing:: Distributing @command{configure} scripts
* Why GNU m4:: Why not use the standard M4?
* Bootstrapping:: Autoconf and GNU M4 require each other?
* Why Not Imake:: Why GNU uses @command{configure} instead of Imake
+* Defining Directories:: Passing @code{datadir} to program
History of Autoconf
@@ -527,8 +528,8 @@
do not have. You must use version 1.4 or later of @sc{gnu} M4.
@xref{Autoconf 1}, for information about upgrading from version 1.
-@xref{History}, for the story of Autoconf's development.
-@xref{Questions}, for answers to some common questions about Autoconf.
+@xref{History}, for the story of Autoconf's development. @xref{FAQ},
+for answers to some common questions about Autoconf.
See the @href{http://www.gnu.org/software/autoconf/autoconf.html,
@@ -13750,10 +13751,10 @@
-@c ================================================ Questions About Autoconf.
+@c =============================== Frequently Asked Questions About Autoconf
-@node Questions
-@chapter Questions About Autoconf
+@node FAQ
+@chapter Frequently Asked Questions About Autoconf
Several questions about Autoconf come up occasionally. Here some of them
are addressed.
@@ -13763,6 +13764,7 @@
* Why GNU m4:: Why not use the standard M4?
* Bootstrapping:: Autoconf and GNU M4 require each other?
* Why Not Imake:: Why GNU uses @command{configure} instead of Imake
+* Defining Directories:: Passing @code{datadir} to program
@end menu
@node Distributing
@@ -13937,6 +13939,74 @@
duplicated, even though they normally are in @command{configure} setups.
@end quotation
+
+@node Defining Directories
+@section How Do I @code{#define} Installation Directories?
+
+@display
+My program needs library files, installed in @code{datadir} and
+similar. If I use
+
+@example
+AC_DEFINE_UNQUOTED([DATADIR], [$datadir],
+ [Define to the read-only architecture-independent
+ data directory.])
+@end example
+
+@noindent
+I get
+
+@example
+#define DATADIR "$@{prefix@}/share"
+@end example
+@end display
+
+As already explained, this behavior is on purpose, mandated by the GNU
+Coding Standards, see @ref{Installation Directory Variables}. There are
+several means to acheive a similar goal:
+
+@itemize @minus
+@item
+Do not use @code{AC_DEFINE} but use your @file{Makefile} to pass the
+actual value of @code{datadir} via compilation flags, see
+@ref{Installation Directory Variables}, for the details.
+
+@item
+This solution can be simplified when compiling a program: you may either
+extend the @code{CPPFLAGS}:
+
+@example
+CPPFLAGS = -DDATADIR=\"$(datadir)\" @@CPPFLAGS@@
+@end example
+
+@noindent
+or create a dedicated header file:
+
+@example
+DISTCLEANFILES = datadir.h
+datadir.h: Makefile
+ echo '#define DATADIR "$(datadir)"' >$@@
+@end example
+
+@item
+Use @code{AC_DEFINE} but have @command{configure} compute the literal
+value of @code{datadir} and others. Many people have wrapped macros to
+automate this task. For instance, the macro @code{AC_DEFINE_DIR} from
+the @href{http://www.gnu.org/software/ac-archive/, Autoconf Macro
+Archive}.
+
+This solution is not conformant with the GNU Coding Standards.
+
+@item
+Note that all the previous solutions hard wire the absolute path to
+these directories in the executables, which is not a good property. You
+may try to compute the paths relatively to @code{prefix}, and try to
+find @code{prefix} at runtime, this way your package is relocatable.
+Some macros are already available to address this issue: see
+@code{adl_COMPUTE_RELATIVE_PATHS} and
+@code{adl_COMPUTE_STANDARD_RELATIVE_PATHS} on the
+@href{http://www.gnu.org/software/ac-archive/, Autoconf Macro Archive}.
+@end itemize
