@node Invoking gnulib-tool
@chapter Invoking gnulib-tool
-@c Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
+@c Copyright (C) 2005-2010 Free Software Foundation, Inc.
@c Permission is granted to copy, distribute and/or modify this document
-@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c under the terms of the GNU Free Documentation License, Version 1.3 or
@c any later version published by the Free Software Foundation; with no
@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
@c Texts. A copy of the license is included in the ``GNU Free
simplifies the management of source files, @file{Makefile.am}s and
@file{configure.ac} in packages incorporating Gnulib modules.
+@file{gnulib-tool} is not installed in a standard directory that is
+contained in the @code{PATH} variable. It needs to be run directly in
+the directory that contains the Gnulib source code. You can do this
+either by specifying the absolute filename of @file{gnulib-tool}, or
+you can also use a symbolic link from a place inside your @code{PATH}
+to the @file{gnulib-tool} file of your preferred and most up-to-date
+Gnulib checkout, like this:
+@smallexample
+$ ln -s $HOME/gnu/src/gnulib.git/gnulib-tool $HOME/bin/gnulib-tool
+@end smallexample
+
Run @samp{gnulib-tool --help} for information. To get familiar with
@command{gnulib-tool} without affecting your sources, you can also try
some commands with the option @samp{--dry-run}; then
a real run without changing anything.
@menu
+* Which modules?:: Determining the needed set of Gnulib modules
* Initial import:: First import of Gnulib modules.
* Modified imports:: Changing the import specification.
* Simple update:: Tracking Gnulib development.
* Source changes:: Impact of Gnulib on your source files.
+* gettextize and autopoint:: Caveat: @code{gettextize} and @code{autopoint} users!
+* Localization:: Handling Gnulib's own message translations.
* VCS Issues:: Integration with Version Control Systems.
+* Unit tests:: Bundling the unit tests of the Gnulib modules.
@end menu
+@node Which modules?
+@section Finding modules
+@cindex Finding modules
+
+There are three ways of finding the names of Gnulib modules that you can use
+in your package:
+
+@itemize
+@item
+You have the complete module list, sorted according to categories, in
+@url{http://www.gnu.org/software/gnulib/MODULES.html}.
+
+@item
+If you are looking for a particular POSIX header or function replacement,
+look in the chapters @ref{Header File Substitutes} and
+@ref{Function Substitutes}. For headers and functions that are provided by
+Glibc but not standardized by POSIX, look in the chapters
+@ref{Glibc Header File Substitutes} and @ref{Glibc Function Substitutes}.
+
+@item
+If you have already found the source file in Gnulib and are looking for the
+module that contains this source file, you can use the command
+@samp{gnulib-tool --find @var{filename}}.
+@end itemize
+
+
@node Initial import
@section Initial import
@cindex initial import
-Gnulib assumes your project uses Autoconf and Automake. Invoking
-@samp{gnulib-tool --import} will copy source files, create a
+Gnulib assumes that your project uses Autoconf. When using Gnulib, you
+will need to have Autoconf and Automake among your build tools. Note that
+while the use of Automake in your project's top level directory is an
+easy way to fulfil the Makefile conventions of the GNU coding standards,
+Gnulib does not require it. But when you use Gnulib, Automake will be
+used at least in a subdirectory of your project.
+
+Invoking @samp{gnulib-tool --import} will copy source files, create a
@file{Makefile.am} to build them, generate a file @file{gnulib-comp.m4} with
Autoconf M4 macro declarations used by @file{configure.ac}, and generate
a file @file{gnulib-cache.m4} containing the cached specification of how
@samp{--lib} command line argument.
@item gl_LGPL
-The presence of this macro corresponds to the @samp{--lgpl} command line
-argument. It takes no arguments.
+The presence of this macro without arguments corresponds to the @samp{--lgpl}
+command line argument. The presence of this macro with an argument (whose
+value must be 2 or 3) corresponds to the @samp{--lgpl=@var{arg}} command line
+argument.
@item gl_LIBTOOL
The presence of this macro corresponds to the @samp{--libtool} command line
and these flags have no effect after any system header file has been included.
+@node gettextize and autopoint
+@section Caveat: @code{gettextize} and @code{autopoint} users
+
+@cindex gettextize, caveat
+@cindex autopoint, caveat
+The programs @code{gettextize} and @code{autopoint}, part of
+GNU @code{gettext}, import or update the internationalization infrastructure.
+Some of this infrastructure, namely ca.@: 20 autoconf macro files and the
+@file{config.rpath} file, is also contained in Gnulib and may be imported
+by @code{gnulib-tool}. The use of @code{gettextize} or @code{autopoint}
+will therefore overwrite some of the files that @code{gnulib-tool} has
+imported, and vice versa.
+
+Avoiding to use @code{gettextize} (manually, as package maintainer) or
+@code{autopoint} (as part of a script like @code{autoreconf} or
+@code{autogen.sh}) is not the solution: These programs also import the
+infrastructure in the @file{po/} and optionally in the @file{intl/} directory.
+
+The copies of the conflicting files in Gnulib are more up-to-date than
+the copies brought in by @code{gettextize} and @code{autopoint}. When a
+new @code{gettext} release is made, the copies of the files in Gnulib will
+be updated immediately.
+
+The solution is therefore:
+
+@enumerate
+@item
+When you run @code{gettextize}, always use the @code{gettextize} from the
+matching GNU gettext release. For the most recent Gnulib checkout, this is
+the newest release found on @url{http://ftp.gnu.org/gnu/gettext/}. For an
+older Gnulib snapshot, it is the release that was the most recent release
+at the time the Gnulib snapshot was taken. Then, after @code{gettextize},
+invoke @code{gnulib-tool}.
+
+@item
+When a script of yours run @code{autopoint}, invoke @code{gnulib-tool}
+afterwards.
+
+@item
+If you get an error message like
+@code{*** error: gettext infrastructure mismatch:
+using a Makefile.in.in from gettext version ...
+but the autoconf macros are from gettext version ...},
+it means that a new GNU gettext release was made, and its autoconf macros
+were integrated into Gnulib and now mismatch the @file{po/} infrastructure.
+In this case, fetch and install the new GNU gettext release and run
+@code{gettextize} followed by @code{gnulib-tool}.
+@end enumerate
+
+
+@node Localization
+@section Handling Gnulib's own message translations
+
+Gnulib provides some functions that emit translatable messages using GNU
+@code{gettext}. The @samp{gnulib} domain at the
+@url{http://translationproject.org/, Translation Project} collects
+translations of these messages, which you should incorporate into your
+own programs.
+
+There are two basic ways to achieve this. The first, and older, method
+is to list all the source files you use from Gnulib in your own
+@file{po/POTFILES.in} file. This will cause all the relevant
+translatable strings to be included in your POT file. When you send
+this POT file to the Translation Project, translators will normally fill
+in the translations of the Gnulib strings from their ``translation
+memory'', and send you back updated PO files.
+
+However, this process is error-prone: you might forget to list some
+source files, or the translator might not be using a translation memory
+and provide a different translation than another translator, or the
+translation might not be kept in sync between Gnulib and your package.
+It is also slow and causes substantial extra work, because a human
+translator must be in the loop for each language and you will need to
+incorporate their work on request.
+
+For these reasons, a new method was designed and is now recommended. If
+you pass the @code{--po-base=@var{directory}} and @code{--po-domain=@var{domain}}
+options to @code{gnulib-tool}, then @code{gnulib-tool} will create a
+separate directory with its own @file{POTFILES.in}, and fetch current
+translations directly from the Translation Project (using
+@command{rsync} or @command{wget}, whichever is available).
+The POT file in this directory will be called
+@file{@var{domain}-gnulib.pot}, depending on the @var{domain} you gave to the
+@code{--po-domain} option (typically the same as the package name).
+This causes these translations to reside in a separate message domain,
+so that they do not clash either with the translations for the main part
+of your package nor with those of other packages on the system that use
+possibly different versions of Gnulib.
+When you use these options, the functions in Gnulib are built
+in such a way that they will always use this domain regardless of the
+default domain set by @code{textdomain}.
+
+In order to use this method, you must -- in each program that might use
+Gnulib code -- add an extra line to the part of the program that
+initializes locale-dependent behavior. Where you would normally write
+something like:
+
+@example
+@group
+ setlocale (LC_ALL, "");
+ bindtextdomain (PACKAGE, LOCALEDIR);
+ textdomain (PACKAGE);
+@end group
+@end example
+
+@noindent
+you should add an additional @code{bindtextdomain} call to inform
+gettext of where the MO files for the extra message domain may be found:
+
+@example
+@group
+ bindtextdomain (PACKAGE "-gnulib", LOCALEDIR);
+@end group
+@end example
+
+(This example assumes that the @var{domain} that you specified
+to @code{gnulib-tool} is the same as the value of the @code{PACKAGE}
+preprocessor macro.)
+
+Since you do not change the @code{textdomain} call, the default message
+domain for your program remains the same and your own use of @code{gettext}
+functions will not be affected.
+
+
@node VCS Issues
@section Issues with Version Control Systems
If a project stores its source files in a version control system (VCS),
-such as CVS, SVN, or Git, one needs to decide which files to commit.
+such as CVS, Subversion, or Git, one needs to decide which files to commit.
-All files created by @code{gnulib-tool}, except @file{gnulib-cache.m4},
-should be treated like generated source files, like for example a
-@file{parser.c} file is generated from @file{parser.y}.
+In principle, all files created by @code{gnulib-tool}, except
+@file{gnulib-cache.m4}, can be treated like generated source files,
+like for example a @file{parser.c} file generated from
+@file{parser.y}. Alternatively, they can be considered source files
+and updated manually.
-@itemize
+Here are the three different approaches in common use. Each has its
+place, and you should use whichever best suits your particular project
+and development methods.
+@enumerate
@item
-In projects which commit all source files, whether generated or not, into
-their VCS, the @code{gnulib-tool} generated files should all be committed.
+In projects which commit all source files, whether generated or not,
+into their VCS, the @code{gnulib-tool} generated files should all be
+committed. In this case, you should pass the option
+@samp{--no-vc-files} to @code{gnulib-tool}, which avoids alteration of
+VCS-related files such as @file{.cvsignore}.
Gnulib also contains files generated by @command{make} (and removed by
-@code{make clean}), using information determined by @command{configure}
-They should not be checked into the VCS, but instead added to
-@file{.cvsignore}. When you have a Gnulib source file of the form
-@file{lib/foo_.h}, the corresponding @file{lib/foo.h} is such a file.
+@code{make clean}), using information determined by
+@command{configure}. For a Gnulib source file of the form
+@file{lib/foo.in.h}, the corresponding @file{lib/foo.h} is such a
+@command{make}-generated file. These should @emph{not} be checked
+into the VCS, but instead added to @file{.cvsignore} or equivalent.
@item
-In projects which customarily omit from their VCS all files that are generated
-from other source files, all these files and directories would not be
-added into the VCS. The only file that must be added to the VCS is
-@file{gnulib-cache.m4} in the M4 macros directory. Also, the script for
-restoring files not in the VCS, customarily called @file{autogen.sh} or
-@file{bootstrap.sh}, will typically contain the statement for restoring
-the omitted files:
+In projects which customarily omit from their VCS all files that are
+generated from other source files, none of these files and directories
+are added into the VCS. The only file that must be added to the VCS
+is @file{gnulib-cache.m4} in the M4 macros directory. Also, the
+script for restoring files not in the VCS, customarily called
+@file{autogen.sh} or @file{bootstrap}, will typically contain the
+statement for restoring the omitted files:
@smallexample
$ gnulib-tool --update
Also it does not report in the ChangeLogs the files that it had to add
because they were missing.
-@end itemize
+Gnulib includes the file @file{build-aux/bootstrap} to aid a developer
+in using this setup. Furthermore, in projects that use git for
+version control, it is possible to use a git submodule containing the
+precise commit of the gnulib repository, so that each developer
+running @file{bootstrap} will get the same version of all
+gnulib-provided files. The location of the submodule can be chosen to
+fit the package's needs; here's how to initially create the submodule
+in the directory @file{.gnulib}:
+
+@smallexample
+$ dir=.gnulib
+$ git submodule add -- git://git.sv.gnu.org/gnulib.git $dir
+$ git config alias.syncsub "submodule foreach git pull origin master"
+@end smallexample
+
+@noindent
+Thereafter, @file{bootstrap} can run this command to update the
+submodule to the recorded checkout level:
+
+@smallexample
+git submodule update --init $dir
+@end smallexample
+
+@noindent
+and a developer can use this sequence to update to a newer version of
+gnulib:
+
+@smallexample
+$ git syncsub
+$ git add $dir
+$ ./bootstrap
+@end smallexample
+
+@item
+Some projects take a ``middle road'': they do commit Gnulib source
+files as in the first approach, but they do not commit other derived
+files, such as a @code{Makefile.in} generated by Automake. This
+increases the size and complexity of the repository, but can help
+occasional contributors by not requiring them to have a full Gnulib
+checkout to do a build, and all developers by ensuring that all
+developers are working with the same version of Gnulib in the
+repository. It also supports multiple Gnulib instances within a
+project. It remains important not to commit the
+@command{make}-generated files, as described above.
+
+@end enumerate
+
+
+@node Unit tests
+@section Bundling the unit tests of the Gnulib modules
+
+You can bundle the unit tests of the Gnulib modules together with your
+package, through the @samp{--with-tests} option. Together with
+@samp{--with-tests}, you also specify the directory for these tests
+through the @samp{--tests-base} option. Of course, you need to add this
+directory to the @code{SUBDIRS} variable in the @code{Makefile.am} of
+the parent directory.
+
+The advantage of having the unit tests bundled is that when your program
+has a problem on a particular platform, running the unit tests may help
+determine quickly if the problem is on Gnulib's side or on your package's
+side. Also, it helps verifying Gnulib's portability, of course.
+
+The unit tests will be compiled and run when the user runs @samp{make check}.
+When the user runs only @samp{make}, the unit tests will not be compiled.
+
+In the @code{SUBDIRS} variable, it is useful to put the Gnulib tests directory
+after the directory containing the other tests, not before:
+
+@smallexample
+SUBDIRS = gnulib-lib src man tests gnulib-tests
+@end smallexample
+
+@noindent
+This will ensure that on platforms where there are test failures in either
+directory, users will see and report the failures from the tests of your
+program.
+
+Note: In packages which use more than one invocation of @code{gnulib-tool}
+in the scope of the same @code{configure.ac}, you cannot use
+@samp{--with-tests}. You will have to use a separate @code{configure.ac}
+in this case.
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