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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 GNU distributions, because GNU gettext is purposely for helping the internationalization of the whole GNU project. So, the maintainer's view presented here presumes that the package already has a `configure.in' file and uses Autoconf.

Nevertheless, GNU gettext may surely be useful for non-GNU packages, 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 GNU packages are distributed as tar files which unpack in a single directory, these are said to be flat distributions. Other GNU 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.

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 GNU translating team (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 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 GNU. 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 `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:

`-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 `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 `NLS' file than the one provided through gettextize, if you have one handy. You may also fetch a more recent copy of file `NLS' 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 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 `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
    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' by its version numbers, exactly as they should appear in the packaged tar file name of your distribution (`gettext-0.10.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':
    ud_GNU_GETTEXT
    
    This call is purposely simple, even if it generates a lot of configure time checking and actions.
  4. Obtain some `libintl.h' header file. Once you called ud_GNU_GETTEXT in `configure.in', use:
    AC_LINK_FILES($nls_cv_header_libgt, $nls_cv_header_intl)
    
    This will create one header file `libintl.h'. The reason for this has to do with the fact that some systems, using the Uniforum message handling functions, already have a file of this name. The AC_LINK_FILES call has not been integrated into the ud_GNU_GETTEXT macro because there can be only one such call in a `configure' file. If you already use it, you will have to merge the needed AC_LINK_FILES within yours, by adding the first argument at the end of the list of your first argument, and adding the second argument at the end of the list of your second argument.
  5. 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],
    [sed -e "/POTFILES =/r po/POTFILES" po/Makefile.in > po/Makefile
    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'. The modification to the second argument ensures that `po/Makefile' gets generated out of the `po/Makefile.in' just created, including in it the `po/POTFILES' produced by ud_GNU_GETTEXT. Two steps are needed because `po/POTFILES' can get lengthy in some packages, too lengthy in fact for being able to merely use an Autoconf substituted variable, as many seds cannot handle very long lines.

`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 ud_LC_MESSAGES, ud_WITH_NLS and ud_GNU_GETTEXT, 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, 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 = @[email protected]
    VERSION = @[email protected]
    
  2. Add file `NLS' to the DISTFILES definition, so the file gets distributed.
  3. Wherever you process subdirectories in your `Makefile.in', be sure you also process @[email protected] and @[email protected], which are replaced respectively by `intl' and `po', or empty when the configuration processes decides these directories should not be processed. 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 @[email protected] src @[email protected]
    
    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) [email protected]) || 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 = @[email protected]
    VERSION = @[email protected]
    
  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 = @[email protected]
    
  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 @[email protected] as a library. An easy way to achieve this is to manage that it gets into LIBS, like this:
    LIBS = @[email protected] @[email protected]
    
    In most GNU packages 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 @[email protected] and @[email protected] in the above example. Instead one has to write this:
    LIBS = ../lib/libsupport.a @[email protected] ../lib/libsupport.a @[email protected]
    
  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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