gettext: AM_GNU_GETTEXT
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). 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])
INTLSYMBOL should always be ‘external’.
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’.
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.
Info Catalog
gettext: autoconf macros
gettext: AM_GNU_GETTEXT_VERSION