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13. The Maintainer's View

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 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.ac' 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.


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13.1 Flat or Non-Flat Directory Structures

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.


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13.2 Prerequisite Works

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.

  • Before attempting to use 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.

  • Your package should use Autoconf and have a `configure.ac' or `configure.in' file. If it does not, you have to learn how. The Autoconf documentation is quite well written, it is a good idea that you print it and get familiar with it.
  • Your C sources should have already been modified according to instructions given earlier in this manual. See section Preparing Program Sources.
  • Your `po/' directory should receive all PO files submitted to you by the translator teams, each having `ll.po' as a name. This is not usually easy to get translation work done before your package gets internationalized and available! Since the cycle has to start somewhere, the easiest for the maintainer is to start with absolutely no PO files, and wait until various translator teams get interested in your package, and submit PO files.

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 ` Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. ' 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.


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13.3 Invoking the gettextize Program

The gettextize program is an interactive tool that helps the maintainer of a package internationalized through GNU gettext. It is used for two purposes:

  • As a wizard, when a package is modified to use GNU gettext for the first time.
  • As a migration tool, for upgrading the GNU gettext support in a package from a previous to a newer version of GNU gettext.

This program performs the following tasks:

  • It copies into the package some files that are consistently and identically needed in every package internationalized through GNU gettext.
  • It performs as many of the tasks mentioned in the next section Files You Must Create or Alter as can be performed automatically.
  • It removes obsolete files and idioms used for previous GNU gettext versions to the form recommended for the current GNU gettext version.
  • It prints a summary of the tasks that ought to be done manually and could not be done automatically by gettextize.

It can be invoked as follows:

gettextize [ option… ] [ directory ]

and accepts the following options:

`-f'
`--force'

Force replacement of files which already exist.

`--intl'

Install the libintl sources in a subdirectory named `intl/'. This libintl will be used to provide internationalization on systems that don't have GNU libintl installed. If this option is omitted, the call to AM_GNU_GETTEXT in `configure.ac' should read: `AM_GNU_GETTEXT([external])', and internationalization will not be enabled on systems lacking GNU gettext.

`--po-dir=dir'

Specify a directory containing PO files. Such a directory contains the translations into various languages of a particular POT file. This option can be specified multiple times, once for each translation domain. If it is not specified, the directory named `po/' is updated.

`--no-changelog'

Don't update or create ChangeLog files. By default, gettextize logs all changes (file additions, modifications and removals) in a file called `ChangeLog' in each affected directory.

`--symlink'

Make symbolic links instead of copying the needed files. This can be useful to save a few kilobytes of disk space, but it requires extra effort to create self-contained tarballs, it may disturb some mechanism the maintainer applies to the sources, and it is likely to introduce bugs when a newer version of gettext is installed on the system.

`-n'
`--dry-run'

Print modifications but don't perform them. All actions that gettextize would normally execute are inhibited and instead only listed on standard output.

`--help'

Display this help and exit.

`--version'

Output version information and exit.

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.

  1. The `ABOUT-NLS' file is copied in the main directory of your package, the one being at the top level. This file gives the main indications about how to install and use the Native Language Support features of your program. You might elect to use a more recent copy of this `ABOUT-NLS' file than the one provided through 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.
  2. A `po/' directory is created for eventually holding all translation files, but initially only containing the file `po/Makefile.in.in' from the GNU 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.

    If `--po-dir' has been specified, this holds for every directory specified through `--po-dir', instead of `po/'.

  3. Only if `--intl' has been specified: A `intl/' directory is created and filled with most of the files originally in the `intl/' directory of the GNU gettext distribution. Also, if option --force (-f) is given, the `intl/' directory is emptied first.
  4. The file `config.rpath' is copied into the directory containing configuration support files. It is needed by the AM_GNU_GETTEXT autoconf macro.
  5. Only if the project is using GNU automake: A set of autoconf macro files is copied into the package's autoconf macro repository, usually in a directory called `m4/'.

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'.

Furthermore, gettextize will update all `Makefile.am' files in each affected directory, as well as the top level `configure.ac' or `configure.in' file.

It is interesting to understand that most new files for supporting GNU gettext facilities in one package go in `intl/', `po/' and `m4/' subdirectories. One distinction between `intl/' and the two other directories is that `intl/' is meant to be completely identical in all packages using GNU gettext, while the other directories will mostly contain package dependent files.

The gettextize program makes backup files for all files it replaces or changes, and also write ChangeLog entries about these changes. This way, the careful maintainer can check after running gettextize whether its changes are acceptable to him, and possibly adjust them. An exception to this rule is the `intl/' directory, which is added or replaced or removed as a whole.

It is important to understand that gettextize can not do the entire job of adapting a package for using GNU gettext. The amount of remaining work depends on whether the package uses GNU automake or not. But in any case, the maintainer should still read the section Files You Must Create or Alter after invoking gettextize.

In particular, if after using `gettexize', you get an error `AC_COMPILE_IFELSE was called before AC_GNU_SOURCE' or `AC_RUN_IFELSE was called before AC_GNU_SOURCE', you can fix it by modifying `configure.ac', as described in `configure.ac' at top level.

It is also important to understand that gettextize is not part of the GNU build system, in the sense that it should not be invoked automatically, and not be invoked by someone who doesn't assume the responsibilities of a package maintainer. For the latter purpose, a separate tool is provided, see Invoking the autopoint Program.


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13.4 Files You Must Create or Alter

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 0.18 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.


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13.4.1 `POTFILES.in' in `po/'

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 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.


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13.4.2 `LINGUAS' in `po/'

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 The Installer's and Distributor's View).

It is recommended that you add the "languages" `en@quot' and `en@boldquot' to the LINGUAS file. en@quot is a variant of English message catalogs (en) which uses real quotation marks instead of the ugly looking asymmetric ASCII substitutes ``' and `''. en@boldquot is a variant of en@quot that additionally outputs quoted pieces of text in a bold font, when used in a terminal emulator which supports the VT100 escape sequences (such as xterm or the Linux console, but not Emacs in M-x shell mode).

These extra message catalogs `en@quot' and `en@boldquot' are constructed automatically, not by translators; to support them, you need the files `Rules-quot', `quot.sed', `boldquot.sed', `en@quot.header', `en@boldquot.header', `insert-header.sin' in the `po/' directory. You can copy them from GNU gettext's `po/' directory; they are also installed by running gettextize.


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13.4.3 `Makevars' in `po/'

The `po/' directory also has a file named `Makevars'. It contains variables that are specific to your project. `po/Makevars' gets inserted into the `po/Makefile' when the latter is created. The variables thus take effect when the POT file is created or updated, and when the message catalogs get installed.

The first three variables 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 first variables defined in `Makevars'.

As an alternative to the XGETTEXT_OPTIONS variables, it is also possible to specify xgettext options through the AM_XGETTEXT_OPTION autoconf macro. See AM_XGETTEXT_OPTION in `po.m4'.


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13.4.4 Extending `Makefile' in `po/'

All files called `Rules-*' in the `po/' directory get appended to the `po/Makefile' when it is created. 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 ` Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. ' and ` Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. '. The effect of ` Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. ' 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 ` Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. ' 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.

Similarly, you can create rules for building message catalogs for the `sr@latin' locale - Serbian written with the Latin alphabet - from those for the `sr' locale - Serbian written with Cyrillic letters. See Invoking the msgfilter Program.


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13.4.5 `configure.ac' at top level

`configure.ac' or `configure.in' - this is the source from which autoconf generates the `configure' script.

  1. Declare the package and version.

    This is done by a set of lines like these:

    PACKAGE=gettext
    VERSION=0.18
    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, 0.18)
    

    Of course, you replace `gettext' with the name of your package, and `0.18' by its version numbers, exactly as they should appear in the packaged tar file name of your distribution (`gettext-0.18.tar.gz', here).

  2. Check for internationalization support.

    Here is the main m4 macro for triggering internationalization support. Just add this line to `configure.ac':

    AM_GNU_GETTEXT
    

    This 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])
    
  3. Have output files created.

    The AC_OUTPUT directive, at the end of your `configure.ac' 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, after doing the recommended modifications, a command like `aclocal -I m4' or `autoconf' or `autoreconf' fails with a trace similar to this:

configure.ac:44: warning: AC_COMPILE_IFELSE was called before AC_GNU_SOURCE
../../lib/autoconf/specific.m4:335: AC_GNU_SOURCE is expanded from...
m4/lock.m4:224: gl_LOCK is expanded from...
m4/gettext.m4:571: gt_INTL_SUBDIR_CORE is expanded from...
m4/gettext.m4:472: AM_INTL_SUBDIR is expanded from...
m4/gettext.m4:347: AM_GNU_GETTEXT is expanded from...
configure.ac:44: the top level
configure.ac:44: warning: AC_RUN_IFELSE was called before AC_GNU_SOURCE

you need to add an explicit invocation of `AC_GNU_SOURCE' in the `configure.ac' file - after `AC_PROG_CC' but before `AM_GNU_GETTEXT', most likely very close to the `AC_PROG_CC' invocation. This is necessary because of ordering restrictions imposed by GNU autoconf.


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13.4.6 `config.guess', `config.sub' at top level

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 the CVS of the `config' project at `http://savannah.gnu.org/'. The commands to fetch them are

$ wget 'http://savannah.gnu.org/cgi-bin/viewcvs/*checkout*/config/config/config.guess'
$ wget 'http://savannah.gnu.org/cgi-bin/viewcvs/*checkout*/config/config/config.sub'

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' or `missing'. All you need to do, other than moving the files, is to add the following line to your `configure.ac'.

AC_CONFIG_AUX_DIR([subdir])

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13.4.7 `mkinstalldirs' at top level

With earlier versions of GNU gettext, you needed to add the GNU `mkinstalldirs' script to your distribution. This is not needed any more. You can remove it if you not also using an automake version older than automake 1.9.


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13.4.8 `aclocal.m4' at top level

If you do not have an `aclocal.m4' file in your distribution, the simplest is to concatenate the files `codeset.m4', `fcntl-o.m4', `gettext.m4', `glibc2.m4', `glibc21.m4', `iconv.m4', `intdiv0.m4', `intl.m4', `intldir.m4', `intlmacosx.m4', `intmax.m4', `inttypes_h.m4', `inttypes-pri.m4', `lcmessage.m4', `lib-ld.m4', `lib-link.m4', `lib-prefix.m4', `lock.m4', `longlong.m4', `nls.m4', `po.m4', `printf-posix.m4', `progtest.m4', `size_max.m4', `stdint_h.m4', `threadlib.m4', `uintmax_t.m4', `visibility.m4', `wchar_t.m4', `wint_t.m4', `xsize.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', `nls.m4', `po.m4', `progtest.m4' need to be concatenated.

If you are not using GNU automake 1.8 or newer, you will need to add a file `mkdirp.m4' from a newer automake distribution to the list of files above.

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.


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13.4.9 `acconfig.h' at top level

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.


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13.4.10 `config.h.in' at top level

The include file template that holds the C macros to be defined by configure is usually called `config.h.in' and may be maintained either manually or automatically.

If gettextize has created an `intl/' directory, this file must be called `config.h.in' and must be at the top level. If, however, you have suppressed the `intl/' directory by calling gettextize without `--intl' option, then you can choose the name of this file and its location freely.

If it is maintained automatically, by use of the `autoheader' program, you need to do nothing about it. This is the case in particular if you are using GNU automake.

If it is maintained manually, and if gettextize has created an `intl/' directory, you should switch to using `autoheader'. The list of C macros to be added for the sake of the `intl/' directory is just too long to be maintained manually; it also changes between different versions of GNU gettext.

If it is maintained manually, and if on the other hand you have suppressed the `intl/' directory by calling gettextize without `--intl' option, then you can get away by adding the following lines to `config.h.in':

/* Define to 1 if translation of program messages to the user's
   native language is requested. */
#undef ENABLE_NLS

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13.4.11 `Makefile.in' at top level

Here are a few modifications you need to make to your main, top-level `Makefile.in' file.

  1. Add the following lines near the beginning of your `Makefile.in', so the `dist:' goal will work properly (as explained further down):
    PACKAGE = @PACKAGE@
    VERSION = @VERSION@
    
  2. Add file `ABOUT-NLS' to the DISTFILES definition, so the file gets distributed.
  3. Wherever you process subdirectories in your `Makefile.in', be sure you also process the subdirectories `intl' and `po'. Special rules in the `Makefiles' take care for the case where no internationalization is wanted.

    If you are using Makefiles, either generated by automake, or hand-written so they carefully follow the GNU coding standards, the effected goals for which the new subdirectories must be handled include `installdirs', `install', `uninstall', `clean', `distclean'.

    Here is an example of a canonical order of processing. In this example, we also define SUBDIRS in Makefile.in for it to be further used in the `dist:' goal.

    SUBDIRS = doc intl lib src po
    

    Note 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.

  4. A delicate point is the `dist:' goal, as both `intl/Makefile' and `po/Makefile' will later assume that the proper directory has been set up from the main `Makefile'. Here is an example at what the `dist:' goal might look like:
    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'.


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13.4.12 `Makefile.in' in `src/'

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':

  1. In view of the `dist:' goal, you should have these lines near the beginning of `src/Makefile.in':
    PACKAGE = @PACKAGE@
    VERSION = @VERSION@
    
  2. If not done already, you should guarantee that top_srcdir gets defined. This will serve for cpp include files. Just add the line:
    top_srcdir = @top_srcdir@
    
  3. You might also want to define 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
    
  4. The main function of your program will normally call bindtextdomain (see see section Triggering gettext Operations), like this:
    bindtextdomain (PACKAGE, LOCALEDIR);
    textdomain (PACKAGE);
    

    To make LOCALEDIR known to the program, add the following lines to `Makefile.in' if you are using Autoconf version 2.60 or newer:

    datadir = @datadir@
    datarootdir= @datarootdir@
    localedir = @localedir@
    DEFS = -DLOCALEDIR=\"$(localedir)\" @DEFS@
    

    or these lines if your version of Autoconf is older than 2.60:

    datadir = @datadir@
    localedir = $(datadir)/locale
    DEFS = -DLOCALEDIR=\"$(localedir)\" @DEFS@
    

    Note that @datadir@ defaults to `$(prefix)/share', thus $(localedir) defaults to `$(prefix)/share/locale'.

  5. You should ensure that the final linking will use @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@
    
  6. You should also ensure that directory `intl/' will be searched for C preprocessor include files in all circumstances. So, you have to manage so both `-I../intl' and `-I$(top_srcdir)/intl' will be given to the C compiler.
  7. Your `dist:' goal has to conform with others. Here is a reasonable definition for it:
    distdir = ../$(PACKAGE)-$(VERSION)/$(subdir)
    dist: Makefile $(DISTFILES)
    	for file in $(DISTFILES); do \
    	  ln $$file $(distdir) 2>/dev/null || cp -p $$file $(distdir) || exit 1; \
    	done
    

Note that if you are using GNU automake, `Makefile.in' is automatically generated from `Makefile.am', and the first three changes and the last change are not necessary. The remaining needed `Makefile.am' modifications are the following:

  1. To make LOCALEDIR known to the program, add the following to `Makefile.am':
    <module>_CPPFLAGS = -DLOCALEDIR=\"$(localedir)\"
    

    for each specific module or compilation unit, or

    AM_CPPFLAGS = -DLOCALEDIR=\"$(localedir)\"
    

    for all modules and compilation units together. Furthermore, if you are using an Autoconf version older then 2.60, add this line to define `localedir':

    localedir = $(datadir)/locale
    
  2. To ensure that the final linking will use @LIBINTL@ or @LTLIBINTL@ as a library, add the following to `Makefile.am':
    <program>_LDADD = @LIBINTL@
    

    for each specific program, or

    LDADD = @LIBINTL@
    

    for all programs together. Remember that when you use libtool to link a program, you need to use @LTLIBINTL@ instead of @LIBINTL@ for that program.

  3. If you have an `intl/' directory, whose contents is created by gettextize, then to ensure that it will be searched for C preprocessor include files in all circumstances, add something like this to `Makefile.am':
    AM_CPPFLAGS = -I../intl -I$(top_srcdir)/intl
    

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13.4.13 `gettext.h' in `lib/'

Internationalization of packages, as provided by GNU gettext, is optional. It can be turned off in two situations:

  • When the installer has specified `./configure --disable-nls'. This can be useful when small binaries are more important than features, for example when building utilities for boot diskettes. It can also be useful in order to get some specific C compiler warnings about code quality with some older versions of GCC (older than 3.0).
  • When the package does not include the intl/ subdirectory, and the libintl.h header (with its associated libintl library, if any) is not already installed on the system, it is preferable 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.


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13.5 Autoconf macros for use in `configure.ac'

GNU gettext installs macros for use in a package's `configure.ac' or `configure.in'. See (autoconf)Top section `Introduction' in The Autoconf Manual. The primary macro is, of course, AM_GNU_GETTEXT.


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13.5.1 AM_GNU_GETTEXT in `gettext.m4'

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. It also invokes AM_PO_SUBDIRS, thus preparing the `po/' directories of the package for building.

AM_GNU_GETTEXT accepts up to three optional arguments. The general syntax is

AM_GNU_GETTEXT([intlsymbol], [needsymbol], [intldir])

intlsymbol can be `external' or `no-libtool'. The default (if it is not specified or empty) is `no-libtool'. intlsymbol should be `external' for packages with no `intl/' directory. For packages with an `intl/' directory, you can either use an intlsymbol equal to `no-libtool', or you can use `external' and override by using the macro AM_GNU_GETTEXT_INTL_SUBDIR elsewhere. The two ways to specify the existence of an `intl/' directory are equivalent. At build time, a static library $(top_builddir)/intl/libintl.a will then 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. If needsymbol is specified and is `need-formatstring-macros', then GNU gettext implementations that don't support the ISO C 99 `<inttypes.h>' formatstring macros will be ignored. Only one needsymbol can be specified. These requirements can also be specified by using the macro AM_GNU_GETTEXT_NEED elsewhere. To specify more than one requirement, just specify the strongest one among them, or invoke the AM_GNU_GETTEXT_NEED macro several times. The hierarchy among the various alternatives is as follows: `need-formatstring-macros' implies `need-ngettext'.

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:

  • Some operating systems have 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.
  • GNU libintl, if installed, is not necessarily already in the search path (CPPFLAGS for the include file search path, LDFLAGS for the library search path).
  • Except for glibc, the operating system's native 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.
  • GNU 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.
  • GNU libintl relies on POSIX/XSI iconv. The macro checks for linker options needed to use iconv and appends them to the LIBINTL and LTLIBINTL variables.

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13.5.2 AM_GNU_GETTEXT_VERSION in `gettext.m4'

The AM_GNU_GETTEXT_VERSION macro declares the version number of the GNU gettext infrastructure that is used by the package.

The use of this macro is optional; only the autopoint program makes use of it (see section Integrating with CVS).


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13.5.3 AM_GNU_GETTEXT_NEED in `gettext.m4'

The AM_GNU_GETTEXT_NEED macro declares a constraint regarding the GNU gettext implementation. The syntax is

AM_GNU_GETTEXT_NEED([needsymbol])

If needsymbol is `need-ngettext', then GNU gettext implementations (in libc or libintl) without the ngettext() function will be ignored. If needsymbol is `need-formatstring-macros', then GNU gettext implementations that don't support the ISO C 99 `<inttypes.h>' formatstring macros will be ignored.

The optional second argument of AM_GNU_GETTEXT is also taken into account.

The AM_GNU_GETTEXT_NEED invocations can occur before or after the AM_GNU_GETTEXT invocation; the order doesn't matter.


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13.5.4 AM_GNU_GETTEXT_INTL_SUBDIR in `intldir.m4'

The AM_GNU_GETTEXT_INTL_SUBDIR macro specifies that the AM_GNU_GETTEXT macro, although invoked with the first argument `external', should also prepare for building the `intl/' subdirectory.

The AM_GNU_GETTEXT_INTL_SUBDIR invocation can occur before or after the AM_GNU_GETTEXT invocation; the order doesn't matter.

The use of this macro requires GNU automake 1.10 or newer and GNU autoconf 2.61 or newer.


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13.5.5 AM_PO_SUBDIRS in `po.m4'

The AM_PO_SUBDIRS macro prepares the `po/' directories of the package for building. This macro should be used in internationalized programs written in other programming languages than C, C++, Objective C, for example sh, Python, Lisp. See Other Programming Languages for a list of programming languages that support localization through PO files.

The AM_PO_SUBDIRS macro determines whether internationalization should be used. If so, it sets the USE_NLS variable to `yes', otherwise to `no'. It also determines the right values for Makefile variables in each `po/' directory.


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13.5.6 AM_XGETTEXT_OPTION in `po.m4'

The AM_XGETTEXT_OPTION macro registers a command-line option to be used in the invocations of xgettext in the `po/' directories of the package.

For example, if you have a source file that defines a function `error_at_line' whose fifth argument is a format string, you can use

AM_XGETTEXT_OPTION([--flag=error_at_line:5:c-format])

to instruct xgettext to mark all translatable strings in `gettext' invocations that occur as fifth argument to this function as `c-format'.

See Invoking the xgettext Program for the list of options that xgettext accepts.

The use of this macro is an alternative to the use of the `XGETTEXT_OPTIONS' variable in `po/Makevars'.


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13.5.7 AM_ICONV in `iconv.m4'

The AM_ICONV macro tests for the presence of the POSIX/XSI 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:

  • Some operating systems have 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.
  • GNU libiconv, if installed, is not necessarily already in the search path (CPPFLAGS for the include file search path, LDFLAGS for the library search path).
  • GNU 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.
  • GNU 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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13.6 Integrating with CVS

Many projects use CVS for distributed development, version control and source backup. This section gives some advice how to manage the uses of cvs, gettextize, autopoint and autoconf.


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13.6.1 Avoiding version mismatch in distributed development

In a project development with multiple developers, using CVS, there should be a single developer who occasionally - when there is desire to upgrade to a new gettext version - runs gettextize and performs the changes listed in Files You Must Create or Alter, and then commits his changes to the CVS.

It is highly recommended that all developers on a project use the same version of GNU gettext in the package. In other words, if a developer runs gettextize, he should go the whole way, make the necessary remaining changes and commit his changes to the CVS. Otherwise the following damages will likely occur:

  • Apparent version mismatch between developers. Since some gettext specific portions in `configure.ac', `configure.in' and Makefile.am, Makefile.in files depend on the gettext version, the use of infrastructure files belonging to different gettext versions can easily lead to build errors.
  • Hidden version mismatch. Such version mismatch can also lead to malfunctioning of the package, that may be undiscovered by the developers. The worst case of hidden version mismatch is that internationalization of the package doesn't work at all.
  • Release risks. All developers implicitly perform constant testing on a package. This is important in the days and weeks before a release. If the guy who makes the release tar files uses a different version of GNU gettext than the other developers, the distribution will be less well tested than if all had been using the same gettext version. For example, it is possible that a platform specific bug goes undiscovered due to this constellation.

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13.6.2 Files to put under CVS version control

There are basically three ways to deal with generated files in the context of a CVS repository, such as `configure' generated from `configure.ac', parser.c generated from parser.y, or po/Makefile.in.in autoinstalled by gettextize or autopoint.

  1. All generated files are always committed into the repository.
  2. All generated files are committed into the repository occasionally, for example each time a release is made.
  3. Generated files are never committed into the repository.

Each of these three approaches has different advantages and drawbacks.

  1. The advantage is that anyone can check out the CVS at any moment and gets a working build. The drawbacks are: 1a. It requires some frequent "cvs commit" actions by the maintainers. 1b. The repository grows in size quite fast.
  2. The advantage is that anyone can check out the CVS, and the usual "./configure; make" will work. The drawbacks are: 2a. The one who checks out the repository needs tools like GNU automake, GNU autoconf, GNU m4 installed in his PATH; sometimes he even needs particular versions of them. 2b. When a release is made and a commit is made on the generated files, the other developers get conflicts on the generated files after doing "cvs update". Although these conflicts are easy to resolve, they are annoying.
  3. The advantage is less work for the maintainers. The drawback is that anyone who checks out the CVS not only needs tools like GNU automake, GNU autoconf, GNU m4 installed in his PATH, but also that he needs to perform a package specific pre-build step before being able to "./configure; make".

For the first and second approach, all files modified or brought in by the occasional gettextize invocation and update should be committed into the CVS.

For the third approach, the maintainer can omit from the CVS repository all the files that gettextize mentions as "copy". Instead, he adds to the `configure.ac' or `configure.in' a line of the form

AM_GNU_GETTEXT_VERSION(0.18)

and adds to the package's pre-build script an invocation of `autopoint'. For everyone who checks out the CVS, this autopoint invocation will copy into the right place the gettext infrastructure files that have been omitted from the CVS.

The version number used as argument to AM_GNU_GETTEXT_VERSION is the version of the gettext infrastructure that the package wants to use. It is also the minimum version number of the `autopoint' program. So, if you write AM_GNU_GETTEXT_VERSION(0.11.5) then the developers can have any version >= 0.11.5 installed; the package will work with the 0.11.5 infrastructure in all developers' builds. When the maintainer then runs gettextize from, say, version 0.12.1 on the package, the occurrence of AM_GNU_GETTEXT_VERSION(0.11.5) will be changed into AM_GNU_GETTEXT_VERSION(0.12.1), and all other developers that use the CVS will henceforth need to have GNU gettext 0.12.1 or newer installed.


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13.6.3 Invoking the autopoint Program

autopoint [option]...

The autopoint program copies standard gettext infrastructure files into a source package. It extracts from a macro call of the form AM_GNU_GETTEXT_VERSION(version), found in the package's `configure.in' or `configure.ac' file, the gettext version used by the package, and copies the infrastructure files belonging to this version into the package.


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13.6.3.1 Options

`-f'
`--force'

Force overwriting of files that already exist.

`-n'
`--dry-run'

Print modifications but don't perform them. All file copying actions that autopoint would normally execute are inhibited and instead only listed on standard output.


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13.6.3.2 Informative output

`--help'

Display this help and exit.

`--version'

Output version information and exit.

autopoint supports the GNU gettext versions from 0.10.35 to the current one, 0.18. In order to apply autopoint to a package using a gettext version newer than 0.18, you need to install this same version of GNU gettext at least.

In packages using GNU automake, an invocation of autopoint should be followed by invocations of aclocal and then autoconf and autoheader. The reason is that autopoint installs some autoconf macro files, which are used by aclocal to create `aclocal.m4', and the latter is used by autoconf to create the package's `configure' script and by autoheader to create the package's `config.h.in' include file template.

The name `autopoint' is an abbreviation of `auto-po-intl-m4'; the tool copies or updates mostly files in the `po', `intl', `m4' directories.


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13.7 Creating a Distribution Tarball

In projects that use GNU automake, the usual commands for creating a distribution tarball, `make dist' or `make distcheck', automatically update the PO files as needed.

If GNU automake is not used, the maintainer needs to perform this update before making a release:

$ ./configure
$ (cd po; make update-po)
$ make distclean

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