GNU gettext utilities - The Maintainer's View

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# 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.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.

## 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.

For now, 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. In the GNU `gettext` distribution, the ``misc/'` directory contains a shell script named ``combine-sh'`. That script may be used for combining all the C files of the ``intl/'` directory into a pair of C files (one ``.c'` and one ``.h'`). Those two generated files would fit more easily in a flat directory structure, and you will then have to add these two files to your project.

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. Only later, once gained more experience adapting GNU `gettext` to flat distributions, we might add some notes about how to proceed in flat situations.

## 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 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 got 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 to 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.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 authentify the origin of the submission as being the representative of the appropriate translating teams of the Translation Project (forward the submission to ``translation@iro.umontreal.ca'` 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 to 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 issue 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.

## Invoking the `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:

``-c'`
``--copy'`
  Copy the needed files instead of making symbolic links. Using links would allow the package to always use the latest `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.
``-f'`
``--force'`
  Force replacement of files which already exist.
``-h'`
``--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). If the ``po/'` directory already exists, it will be preserved along with the files it contains, and only ``Makefile.in.in'` will be overwritten.
3. 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.

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.

## 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` 0.10.35 distribution itself. You may indeed refer to the source code of the GNU `gettext` package, as it is intended to be a good example and master implementation for using its own functionality.

### ``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/gettextp.c
    src/msgfmt.c
    src/xgettext.c

Dashed comments and white lines are ignored. All other lines list those source files containing strings marked for translation (see section How Marks Appears in Sources), in a notation relative to the top level of your whole distribution, rather than the location of the ``POTFILES.in'` file itself.

### ``configure.in'` at top level

1. Declare the package and version. This is done by a set of lines like these:

       PACKAGE=gettext
       VERSION=0.10.35
       AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
       AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
       AC_SUBST(PACKAGE)
       AC_SUBST(VERSION)

   Of course, you replace ``gettext'` with the name of your package, and ``0.10.35'` by its version numbers, exactly as they should appear in the packaged `tar` file name of your distribution (``gettext-0.10.35.tar.gz'`, here).
2. Declare the available translations. This is done by defining `ALL_LINGUAS` to the white separated, quoted list of available languages, in a single line, like this:

       ALL_LINGUAS="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 `ALL_LINGUAS` in ``configure.in'`, but rather by using the `LINGUAS` environment variable (see section Magic for Installers).
3. Check for internationalization support. Here is the main `m4` macro for triggering internationalization support. Just add this line to ``configure.in'`:

       AM_GNU_GETTEXT

   This call is purposely simple, even if it generates a lot of configure time checking and actions.
4. Have output files created. The `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'`.

### ``aclocal.m4'` at top level

If you do not have an ``aclocal.m4'` file in your distribution, the simplest is taking a copy of ``aclocal.m4'` from GNU `gettext`. But to be precise, you only need macros `AM_LC_MESSAGES`, `AM_WITH_NLS` and `AM_GNU_GETTEXT`, and `AM_PATH_PROG_WITH_TEST`, which is called by `AM_WITH_NLS`, so you may use an editor and remove macros you do not need.

If you already have an ``aclocal.m4'` file, then you will have to merge the said macros into your ``aclocal.m4'`. Note that if you are upgrading from a previous release of GNU `gettext`, you should most probably replace the said macros, 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.

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`.

### ``acconfig.h'` at top level

If you do not have an ``acconfig.h'` file in your distribution, the simplest is use take a copy of ``acconfig.h'` from GNU `gettext`. But to be precise, you only need the lines and comments for `ENABLE_NLS`, `HAVE_CATGETS`, `HAVE_GETTEXT` and `HAVE_LC_MESSAGES`, `HAVE_STPCPY`, `PACKAGE` and `VERSION`, so you may use an editor and remove everything else. If you already have an ``acconfig.h'` file, then you should merge the said definitions into your ``acconfig.h'`.

### ``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 dir 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 lib @INTLSUB@ src @POSUB@

   that you will have to adapt to your own package.
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)

### ``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. You should ensure that the final linking will use `@INTLLIBS@` as a library. An easy way to achieve this is to manage that it gets into `LIBS`, like this:

       LIBS = @INTLLIBS@ @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 it is not enough to place the support library (say ``libsupport.a'`) just between the `@INTLLIBS@` and `@LIBS@` in the above example. Instead one has to write this:

       LIBS = ../lib/libsupport.a @INTLLIBS@ ../lib/libsupport.a @LIBS@

5. 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.
6. 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); \
       	done

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