1# init-package-version.m4 serial 1 (gettext-0.18)
2dnl Copyright (C) 1992-2009 Free Software Foundation, Inc.
3dnl This file is free software, distributed under the terms of the GNU
4dnl General Public License.  As a special exception to the GNU General
5dnl Public License, this file may be distributed as part of a program
6dnl that contains a configuration script generated by Autoconf, under
7dnl the same distribution terms as the rest of that program.
8
9# Make it possible to pass version numbers extracted from a file in
10# $(srcdir) to autoconf.
11#
12# Autoconf insists on passing the package name and version number to
13# every generated .h file and every Makefile. This was a reasonable
14# design at times when a version number was changed only once a month.
15# Nowadays, people often assign a new version number once a week, or
16# even change it each time a 'git' commit is made. Regenerating all
17# the files that depend on configure.ac (aclocal.m4, configure,
18# config.status, config.h, all Makefiles) may take 15 minutes. These
19# delays can severely hamper development.
20#
21# An alternative is to store the version number in a file in $(srcdir)
22# that is separate from configure.ac. It can be a data file, a shell
23# script, a .m4 file, or other. The essential point is that the maintainer
24# is responsible for creating Makefile dependencies to this version file
25# for every file that needs to be rebuilt when the version changes. This
26# typically includes
27#   - distributable documentation files that carry the version number,
28# but does not include
29#   - aclocal.m4, configure, config.status, config.h, all Makefiles,
30#   - executables.
31#
32# autoconf and automake make it hard to follow this approach:
33#
34# - If AC_INIT is used with arguments, there is a chicken-and-egg problem:
35#   The arguments need to be read from a file in $(srcdir). The location
36#   of $(srcdir) is only determined by AC_CONFIG_SRCDIR. AC_CONFIG_SRCDIR
37#   can only appear after AC_INIT (otherwise aclocal gives an error:
38#   "error: m4_defn: undefined macro: _m4_divert_diversion").
39#   Furthermore, the arguments passed to AC_INIT must be literals; for
40#   example, the assignment to PACKAGE_VERSION looks like this:
41#     [PACKAGE_VERSION=']AC_PACKAGE_VERSION[']
42#
43# - If AC_INIT is used without arguments:
44#   Automake provides its own variables, PACKAGE and VERSION, and uses them
45#   instead of PACKAGE_NAME and PACKAGE_VERSION that come from Autoconf.
46#   - If AM_INIT_AUTOMAKE is used with two arguments, automake options
47#     like 'silent-rules' cannot be specified.
48#   - If AM_INIT_AUTOMAKE is used in its one-argument form or without
49#     arguments at all, it triggers an error
50#     "error: AC_INIT should be called with package and version arguments".
51#   - If AM_INIT_AUTOMAKE is used in its one-argument form or without
52#     arguments at all, and _AC_INIT_PACKAGE is used before it, with
53#     the package and version number from the file as arguments, we get
54#     a warning: "warning: AC_INIT: not a literal: $VERSION_NUMBER".
55#     The arguments passed to _AC_INIT_PACKAGE must be literals.
56#
57# With the macro defined in this file, the approach can be coded like this:
58#
59#   AC_INIT
60#   AC_CONFIG_SRCDIR(WITNESS)
61#   . $srcdir/../version.sh
62#   gl_INIT_PACKAGE(PACKAGE, $VERSION_NUMBER)
63#   AM_INIT_AUTOMAKE([OPTIONS])
64
65# gl_INIT_PACKAGE(PACKAGE-NAME, VERSION)
66# --------------------------------------
67# followed by an AM_INIT_AUTOMAKE invocation,
68# is like calling AM_INIT_AUTOMAKE(PACKAGE-NAME, VERSION)
69# except that it can use computed non-literal arguments.
70AC_DEFUN([gl_INIT_PACKAGE],
71[
72  AC_BEFORE([$0], [AM_INIT_AUTOMAKE])
73  dnl Redefine AM_INIT_AUTOMAKE.
74  m4_define([gl_AM_INIT_AUTOMAKE],
75    m4_bpatsubst(m4_dquote(
76        m4_bpatsubst(m4_dquote(
77            m4_bpatsubst(m4_dquote(
78                m4_defn([AM_INIT_AUTOMAKE])),
79              [AC_PACKAGE_NAME], [gl_INIT_DUMMY])),
80          [AC_PACKAGE_TARNAME], [gl_INIT_DUMMY])),
81      [AC_PACKAGE_VERSION], [gl_INIT_DUMMY])
82    [AC_SUBST([PACKAGE], [$1])
83     AC_SUBST([VERSION], [$2])
84    ])
85  m4_define([AM_INIT_AUTOMAKE],
86    m4_defn([gl_RPL_INIT_AUTOMAKE]))
87])
88m4_define([gl_INIT_DUMMY], [])
89AC_DEFUN([gl_RPL_INIT_AUTOMAKE], [
90  m4_ifval([$2],
91    [m4_fatal([After gl_INIT_PACKAGE, the two-argument form of AM_INIT_AUTOMAKE cannot be used.])])
92  gl_AM_INIT_AUTOMAKE([$1 no-define])
93  m4_if(m4_index([ $1 ], [ no-define ]), [-1],
94    [AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE", [Name of package])
95     AC_DEFINE_UNQUOTED(VERSION, "$VERSION", [Version number of package])
96    ])
97])
98