The maintainer of a package has many responsibilities. One of them is ensuring that the package will install easily on many platforms, and that the magic we described earlier (see section 9 The User's View) will work for installers and end users.
Of course, there are many possible ways by which GNU gettext
might be integrated in a distribution, and this chapter does not cover
them in all generality. Instead, it details one possible approach which
is especially adequate for many free software distributions following GNU
standards, or even better, Gnits standards, because GNU gettext
is purposely for helping the internationalization of the whole GNU
project, and as many other good free packages as possible. So, the
maintainer's view presented here presumes that the package already has
a `configure.in´ file and uses GNU Autoconf.
Nevertheless, GNU gettext may surely be useful for free packages
not following GNU standards and conventions, but the maintainers of such
packages might have to show imagination and initiative in organizing
their distributions so gettext work for them in all situations.
There are surely many, out there.
Even if gettext methods are now stabilizing, slight adjustments
might be needed between successive gettext versions, so you
should ideally revise this chapter in subsequent releases, looking
for changes.
Some free software packages are distributed as tar files which unpack
in a single directory, these are said to be flat distributions.
Other free software packages have a one level hierarchy of subdirectories, using
for example a subdirectory named `doc/´ for the Texinfo manual and
man pages, another called `lib/´ for holding functions meant to
replace or complement C libraries, and a subdirectory `src/´ for
holding the proper sources for the package. These other distributions
are said to be non-flat.
We cannot say much about flat distributions. A flat
directory structure has the disadvantage of increasing the difficulty
of updating to a new version of GNU gettext. Also, if you have
many PO files, this could somewhat pollute your single directory.
Also, GNU gettext's libintl sources consist of C sources, shell
scripts, sed scripts and complicated Makefile rules, which don't
fit well into an existing flat structure. For these reasons, we
recommend to use non-flat approach in this case as well.
Maybe because GNU gettext itself has a non-flat structure,
we have more experience with this approach, and this is what will be
described in the remaining of this chapter. Some maintainers might
use this as an opportunity to unflatten their package structure.
There are some works which are required for using GNU gettext
in one of your package. These works have some kind of generality
that escape the point by point descriptions used in the remainder
of this chapter. So, we describe them here.
gettextize you should install some
other packages first.
Ensure that recent versions of GNU m4, GNU Autoconf and GNU
gettext are already installed at your site, and if not, proceed
to do this first. If you get to install these things, beware that
GNU m4 must be fully installed before GNU Autoconf is even
configured.
To further ease the task of a package maintainer the automake
package was designed and implemented. GNU gettext now uses this
tool and the `Makefile´s in the `intl/´ and `po/´
therefore know about all the goals necessary for using automake
and `libintl´ in one project.
Those four packages are only needed by you, as a maintainer; the
installers of your own package and end users do not really need any of
GNU m4, GNU Autoconf, GNU gettext, or GNU automake
for successfully installing and running your package, with messages
properly translated. But this is not completely true if you provide
internationalized shell scripts within your own package: GNU
gettext shall then be installed at the user site if the end users
want to see the translation of shell script messages.
It is worth adding here a few words about how the maintainer should ideally behave with PO files submissions. As a maintainer, your role is to authenticate the origin of the submission as being the representative of the appropriate translating teams of the Translation Project (forward the submission to `[email protected]´ in case of doubt), to ensure that the PO file format is not severely broken and does not prevent successful installation, and for the rest, to merely put these PO files in `po/´ for distribution.
As a maintainer, you do not have to take on your shoulders the responsibility of checking if the translations are adequate or complete, and should avoid diving into linguistic matters. Translation teams drive themselves and are fully responsible of their linguistic choices for the Translation Project. Keep in mind that translator teams are not driven by maintainers. You can help by carefully redirecting all communications and reports from users about linguistic matters to the appropriate translation team, or explain users how to reach or join their team. The simplest might be to send them the `ABOUT-NLS´ file.
Maintainers should never ever apply PO file bug reports themselves, short-cutting translation teams. If some translator has difficulty to get some of her points through her team, it should not be an option for her to directly negotiate translations with maintainers. Teams ought to settle their problems themselves, if any. If you, as a maintainer, ever think there is a real problem with a team, please never try to solve a team's problem on your own.
gettextize Program
Some files are consistently and identically needed in every package
internationalized through GNU gettext. As a matter of
convenience, the gettextize program puts all these files right
in your package. This program has the following synopsis:
gettextize [ option... ] [ directory ]
and accepts the following options:
gettext code
available on the system, but it might disturb some mechanism the
maintainer is used to apply to the sources. Because running
gettextize is easy there shouldn't be problems with using copies.
AM_GNU_GETTEXT in `configure.in´ should read:
`AM_GNU_GETTEXT([external])´, and internationalization will not
be enabled on systems lacking GNU gettext.
gettextize
logs all changes (file additions, modifications ans removals) in a
file called `ChangeLog´ in each affected directory.
If directory is given, this is the top level directory of a
package to prepare for using GNU gettext. If not given, it
is assumed that the current directory is the top level directory of
such a package.
The program gettextize provides the following files. However,
no existing file will be replaced unless the option --force
(-f) is specified.
gettextize,
if you have one handy. You may also fetch a more recent copy of file
`ABOUT-NLS´ from Translation Project sites, and from most GNU
archive sites.
gettext distribution.
(beware the double `.in´ in the file name) and a few auxiliary
files. If the `po/´ directory already exists, it will be preserved
along with the files it contains, and only `Makefile.in.in´ and
the auxiliary files will be overwritten.
gettext
distribution. Also, if option --force (-f) is given,
the `intl/´ directory is emptied first.
AM_GNU_GETTEXT
autoconf macro.
If your site support symbolic links, gettextize will not
actually copy the files into your package, but establish symbolic
links instead. This avoids duplicating the disk space needed in
all packages. Merely using the `-h´ option while creating the
tar archive of your distribution will resolve each link by an
actual copy in the distribution archive. So, to insist, you really
should use `-h´ option with tar within your dist
goal of your main `Makefile.in´.
It is interesting to understand that most new files for supporting
GNU gettext facilities in one package go in `intl/´
and `po/´ subdirectories. One distinction between these two
directories is that `intl/´ is meant to be completely identical
in all packages using GNU gettext, while all newly created
files, which have to be different, go into `po/´. There is a
common `Makefile.in.in´ in `po/´, because the `po/´
directory needs its own `Makefile´, and it has been designed so
it can be identical in all packages.
Besides files which are automatically added through gettextize,
there are many files needing revision for properly interacting with
GNU gettext. If you are closely following GNU standards for
Makefile engineering and auto-configuration, the adaptations should
be easier to achieve. Here is a point by point description of the
changes needed in each.
So, here comes a list of files, each one followed by a description of
all alterations it needs. Many examples are taken out from the GNU
gettext 0.11.2 distribution itself, or from the GNU
hello distribution (http://www.franken.de/users/gnu/ke/hello
or http://www.gnu.franken.de/ke/hello/) You may indeed
refer to the source code of the GNU gettext and GNU hello
packages, as they are intended to be good examples for using GNU
gettext functionality.
The `po/´ directory should receive a file named `POTFILES.in´. This file tells which files, among all program sources, have marked strings needing translation. Here is an example of such a file:
# List of source files containing translatable strings. # Copyright (C) 1995 Free Software Foundation, Inc. # Common library files lib/error.c lib/getopt.c lib/xmalloc.c # Package source files src/gettext.c src/msgfmt.c src/xgettext.c
Hash-marked comments and white lines are ignored. All other lines list those source files containing strings marked for translation (see section 3.3 How Marks Appear in Sources), in a notation relative to the top level of your whole distribution, rather than the location of the `POTFILES.in´ file itself.
When a C file is automatically generated by a tool, like flex or
bison, that doesn't introduce translatable strings by itself,
it is recommended to list in `po/POTFILES.in´ the real source file
(ending in `.l´ in the case of flex, or in `.y´ in the
case of bison), not the generated C file.
The `po/´ directory should also receive a file named `LINGUAS´. This file contains the list of available translations. It is a whitespace separated list. Hash-marked comments and white lines are ignored. Here is an example file:
# Set of available languages. de fr
This example means that German and French PO files are available, so
that these languages are currently supported by your package. If you
want to further restrict, at installation time, the set of installed
languages, this should not be done by modifying the `LINGUAS´ file,
but rather by using the LINGUAS environment variable
(see section 9.2 Magic for Installers).
The `po/´ directory also has a file named `Makevars´. It can be left unmodified if your package has a single message domain and, accordingly, a single `po/´ directory. Only packages which have multiple `po/´ directories at different locations need to adjust the three variables defined in `Makevars´.
`po/Makevars´ gets inserted into the `po/Makefile´ when the latter is created. At the same time, all files called `Rules-*´ in the `po/´ directory get appended to the `po/Makefile´. They present an opportunity to add rules for special PO files to the Makefile, without needing to mess with `po/Makefile.in.in´.
GNU gettext comes with a `Rules-quot´ file, containing rules for
building catalogs `[email protected]´ and `[email protected]´. The
effect of `[email protected]´ is that people who set their LANGUAGE
environment variable to `en@quot´ will get messages with proper
looking symmetric Unicode quotation marks instead of abusing the ASCII
grave accent and the ASCII apostrophe for indicating quotations. To
enable this catalog, simply add en@quot to the `po/LINGUAS´
file. The effect of `[email protected]´ is that people who set
LANGUAGE to `en@boldquot´ will get not only proper quotation
marks, but also the quoted text will be shown in a bold font on terminals
and consoles. This catalog is useful only for command-line programs, not
GUI programs. To enable it, similarly add en@boldquot to the
`po/LINGUAS´ file.
`configure.in´ or `configure.ac´ - this is the source from which
autoconf generates the `configure´ script.
PACKAGE=gettext VERSION=0.11.2 AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE") AC_DEFINE_UNQUOTED(VERSION, "$VERSION") AC_SUBST(PACKAGE) AC_SUBST(VERSION)or, if you are using GNU
automake, by a line like this:
AM_INIT_AUTOMAKE(gettext, 0.11.2)Of course, you replace `gettext´ with the name of your package, and `0.11.2´ by its version numbers, exactly as they should appear in the packaged
tar file name of your distribution
(`gettext-0.11.2.tar.gz´, here).
m4 macro for triggering internationalization
support. Just add this line to `configure.in´:
AM_GNU_GETTEXTThis call is purposely simple, even if it generates a lot of configure time checking and actions. If you have suppressed the `intl/´ subdirectory by calling
gettextize without `--intl´ option, this call should read
AM_GNU_GETTEXT([external])
AC_OUTPUT directive, at the end of your `configure.in´
file, needs to be modified in two ways:
AC_OUTPUT([existing configuration files intl/Makefile po/Makefile.in], [existing additional actions])The modification to the first argument to
AC_OUTPUT asks
for substitution in the `intl/´ and `po/´ directories.
Note the `.in´ suffix used for `po/´ only. This is because
the distributed file is really `po/Makefile.in.in´.
If you have suppressed the `intl/´ subdirectory by calling
gettextize without `--intl´ option, then you don't need to
add intl/Makefile to the AC_OUTPUT line.
If you haven't suppressed the `intl/´ subdirectory, you need to add the GNU `config.guess´ and `config.sub´ files to your distribution. They are needed because the `intl/´ directory has platform dependent support for determining the locale's character encoding and therefore needs to identify the platform.
You can obtain the newest version of `config.guess´ and
`config.sub´ from `ftp://ftp.gnu.org/pub/gnu/config/´.
Less recent versions are also contained in the GNU automake and
GNU libtool packages.
Normally, `config.guess´ and `config.sub´ are put at the top level of a distribution. But it is also possible to put them in a subdirectory, altogether with other configuration support files like `install-sh´, `ltconfig´, `ltmain.sh´, `mkinstalldirs´ or `missing´. All you need to do, other than moving the files, is to add the following line to your `configure.in´.
AC_CONFIG_AUX_DIR([subdir])
If you do not have an `aclocal.m4´ file in your distribution,
the simplest is to concatenate the files `codeset.m4´,
`gettext.m4´, `glibc21.m4´, `iconv.m4´, `isc-posix.m4´,
`lcmessage.m4´, `lib-ld.m4´, `lib-link.m4´,
`lib-prefix.m4´, `progtest.m4´ from GNU gettext's
`m4/´ directory into a single file. If you have suppressed the
`intl/´ directory, only `gettext.m4´, `iconv.m4´,
`lib-ld.m4´, `lib-link.m4´, `lib-prefix.m4´,
`progtest.m4´ need to be concatenated.
If you already have an `aclocal.m4´ file, then you will have
to merge the said macro files into your `aclocal.m4´. Note that if
you are upgrading from a previous release of GNU gettext, you
should most probably replace the macros (AM_GNU_GETTEXT,
etc.), as they usually
change a little from one release of GNU gettext to the next.
Their contents may vary as we get more experience with strange systems
out there.
If you are using GNU automake 1.5 or newer, it is enough to put
these macro files into a subdirectory named `m4/´ and add the line
ACLOCAL_AMFLAGS = -I m4
to your top level `Makefile.am´.
These macros check for the internationalization support functions
and related informations. Hopefully, once stabilized, these macros
might be integrated in the standard Autoconf set, because this
piece of m4 code will be the same for all projects using GNU
gettext.
Earlier GNU gettext releases required to put definitions for
ENABLE_NLS, HAVE_GETTEXT and HAVE_LC_MESSAGES,
HAVE_STPCPY, PACKAGE and VERSION into an
`acconfig.h´ file. This is not needed any more; you can remove
them from your `acconfig.h´ file unless your package uses them
independently from the `intl/´ directory.
Here are a few modifications you need to make to your main, top-level `Makefile.in´ file.
PACKAGE = @PACKAGE@ VERSION = @VERSION@
DISTFILES definition, so the file gets
distributed.
SUBDIRS in Makefile.in for it
to be further used in the `dist:´ goal.
SUBDIRS = doc intl lib src poNote that you must arrange for `make´ to descend into the
intl directory before descending into other directories containing
code which make use of the libintl.h header file. For this
reason, here we mention intl before lib and src.
distdir = $(PACKAGE)-$(VERSION) dist: Makefile rm -fr $(distdir) mkdir $(distdir) chmod 777 $(distdir) for file in $(DISTFILES); do \ ln $$file $(distdir) 2>/dev/null || cp -p $$file $(distdir); \ done for subdir in $(SUBDIRS); do \ mkdir $(distdir)/$$subdir || exit 1; \ chmod 777 $(distdir)/$$subdir; \ (cd $$subdir && $(MAKE) $@) || exit 1; \ done tar chozf $(distdir).tar.gz $(distdir) rm -fr $(distdir)
Note that if you are using GNU automake, `Makefile.in´ is
automatically generated from `Makefile.am´, and all needed changes
to `Makefile.am´ are already made by running `gettextize´.
Some of the modifications made in the main `Makefile.in´ will also be needed in the `Makefile.in´ from your package sources, which we assume here to be in the `src/´ subdirectory. Here are all the modifications needed in `src/Makefile.in´:
PACKAGE = @PACKAGE@ VERSION = @VERSION@
top_srcdir
gets defined. This will serve for cpp include files. Just add
the line:
top_srcdir = @top_srcdir@
subdir as `src´, later
allowing for almost uniform `dist:´ goals in all your
`Makefile.in´. At list, the `dist:´ goal below assume that
you used:
subdir = src
main function of your program will normally call
bindtextdomain (see see section 3.1 Triggering gettext Operations), like this:
bindtextdomain (PACKAGE, LOCALEDIR);To make LOCALEDIR known to the program, add the following lines to Makefile.in:
datadir = @datadir@ localedir = $(datadir)/locale DEFS = -DLOCALEDIR=\"$(localedir)\" @DEFS@Note that
@datadir@ defaults to `$(prefix)/share´, thus
$(localedir) defaults to `$(prefix)/share/locale´.
@LIBINTL@ or
@LTLIBINTL@ as a library. @LIBINTL@ is for use without
libtool, @LTLIBINTL@ is for use with libtool. An
easy way to achieve this is to manage that it gets into LIBS, like
this:
LIBS = @LIBINTL@ @LIBS@In most packages internationalized with GNU
gettext, one will
find a directory `lib/´ in which a library containing some helper
functions will be build. (You need at least the few functions which the
GNU gettext Library itself needs.) However some of the functions
in the `lib/´ also give messages to the user which of course should be
translated, too. Taking care of this, the support library (say
`libsupport.a´) should be placed before @LIBINTL@ and
@LIBS@ in the above example. So one has to write this:
LIBS = ../lib/libsupport.a @LIBINTL@ @LIBS@
distdir = ../$(PACKAGE)-$(VERSION)/$(subdir) dist: Makefile $(DISTFILES) for file in $(DISTFILES); do \ ln $$file $(distdir) 2>/dev/null || cp -p $$file $(distdir); \ done
Internationalization of packages, as provided by GNU gettext, is
optional. It can be turned off in two situations:
intl/ subdirectory, and the
libintl.h header (with its associated libintl library, if any) is not
already installed on the system, it is preferrable that the package builds
without internationalization support, rather than to give a compilation
error.
A C preprocessor macro can be used to detect these two cases. Usually,
when libintl.h was found and not explicitly disabled, the
ENABLE_NLS macro will be defined to 1 in the autoconf generated
configuration file (usually called `config.h´). In the two negative
situations, however, this macro will not be defined, thus it will evaluate
to 0 in C preprocessor expressions.
`gettext.h´ is a convenience header file for conditional use of
`<libintl.h>´, depending on the ENABLE_NLS macro. If
ENABLE_NLS is set, it includes `<libintl.h>´; otherwise it
defines no-op substitutes for the libintl.h functions. We recommend
the use of "gettext.h" over direct use of `<libintl.h>´,
so that portability to older systems is guaranteed and installers can
turn off internationalization if they want to. In the C code, you will
then write
#include "gettext.h"
instead of
#include <libintl.h>
The location of gettext.h is usually in a directory containing
auxiliary include files. In many GNU packages, there is a directory
`lib/´ containing helper functions; `gettext.h´ fits there.
In other packages, it can go into the `src´ directory.
Do not install the gettext.h file in public locations. Every
package that needs it should contain a copy of it on its own.
GNU gettext installs macros for use in a package's
`configure.in´ or `configure.ac´.
See section `Introduction' in The Autoconf Manual.
The primary macro is, of course, AM_GNU_GETTEXT.
The AM_GNU_GETTEXT macro tests for the presence of the GNU gettext
function family in either the C library or a separate libintl
library (shared or static libraries are both supported) or in the package's
`intl/´ directory.
AM_GNU_GETTEXT accepts up to three optional arguments. The general
syntax is
AM_GNU_GETTEXT([intlsymbol], [needsymbol], [intldir])
intlsymbol can be one of `external´, `no-libtool´,
`use-libtool´. The default (if it is not specified or empty) is
`no-libtool´. intlsymbol should be `external´ for packages
with no `intl/´ directory, and `no-libtool´ or `use-libtool´
for packages with an `intl/´ directory. If intlsymbol is
`use-libtool´, then a libtool library
$(top_builddir)/intl/libintl.la will be created (shared and/or static,
depending on --{enable,disable}-{shared,static} and on the
presence of AM_DISABLE_SHARED). If intlsymbol is
`no-libtool´, a static library
$(top_builddir)/intl/libintl.a will be created.
If needsymbol is specified and is `need-ngettext´, then GNU
gettext implementations (in libc or libintl) without the ngettext()
function will be ignored.
intldir is used to find the intl libraries. If empty, the value `$(top_builddir)/intl/´ is used.
The AM_GNU_GETTEXT macro determines whether GNU gettext is
available and should be used. If so, it sets the USE_NLS variable
to `yes´; it defines ENABLE_NLS to 1 in the autoconf
generated configuration file (usually called `config.h´); it sets
the variables LIBINTL and LTLIBINTL to the linker options
for use in a Makefile (LIBINTL for use without libtool,
LTLIBINTL for use with libtool); it adds an `-I´ option to
CPPFLAGS if necessary. In the negative case, it sets
USE_NLS to `no´; it sets LIBINTL and LTLIBINTL
to empty and doesn't change CPPFLAGS.
The complexities that AM_GNU_GETTEXT deals with are the following:
gettext in the C library, for example
glibc. Some have it in a separate library libintl. GNU libintl
might have been installed as part of the GNU gettext package.
libintl, if installed, is not necessarily already in the search
path (CPPFLAGS for the include file search path, LDFLAGS for
the library search path).
gettext cannot
exploit the GNU mo files, doesn't have the necessary locale dependency
features, and cannot convert messages from the catalog's text encoding
to the user's locale encoding.
libintl, if installed, is not necessarily already in the
run time library search path. To avoid the need for setting an environment
variable like LD_LIBRARY_PATH, the macro adds the appropriate
run time search path options to the LIBINTL and LTLIBINTL
variables. This works on most systems, but not on some operating systems
with limited shared library support, like SCO.
libintl relies on POSIX iconv. The macro checks for
linker options needed to use iconv and appends them to the LIBINTL
and LTLIBINTL variables.
The AM_ICONV macro tests for the presence of the POSIX
iconv function family in either the C library or a separate
libiconv library. If found, it sets the am_cv_func_iconv
variable to `yes´; it defines HAVE_ICONV to 1 in the autoconf
generated configuration file (usually called `config.h´); it defines
ICONV_CONST to `const´ or to empty, depending on whether the
second argument of iconv() is of type `const char **´ or
`char **´; it sets the variables LIBICONV and
LTLIBICONV to the linker options for use in a Makefile
(LIBICONV for use without libtool, LTLIBICONV for use with
libtool); it adds an `-I´ option to CPPFLAGS if
necessary. If not found, it sets LIBICONV and LTLIBICONV to
empty and doesn't change CPPFLAGS.
The complexities that AM_ICONV deals with are the following:
iconv in the C library, for example
glibc. Some have it in a separate library libiconv, for example
OSF/1 or FreeBSD. Regardless of the operating system, GNU libiconv
might have been installed. In that case, it should be used instead of the
operating system's native iconv.
libiconv, if installed, is not necessarily already in the search
path (CPPFLAGS for the include file search path, LDFLAGS for
the library search path).
libiconv is binary incompatible with some operating system's
native iconv, for example on FreeBSD. Use of an `iconv.h´
and `libiconv.so´ that don't fit together would produce program
crashes.
libiconv, if installed, is not necessarily already in the
run time library search path. To avoid the need for setting an environment
variable like LD_LIBRARY_PATH, the macro adds the appropriate
run time search path options to the LIBICONV variable. This works
on most systems, but not on some operating systems with limited shared
library support, like SCO.
`iconv.m4´ is distributed with the GNU gettext package because `gettext.m4´ relies on it.
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