Gettext/AM 005fGNU 005fGETTEXT
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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). 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 librarylibintl
. GNUlibintl
might have been installed as part of the GNUgettext
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 likeLD_LIBRARY_PATH
, the macro adds the appropriate run time search path options to theLIBINTL
andLTLIBINTL
variables. This works on most systems, but not on some operating systems with limited shared library support, like SCO. - GNU
libintl
relies on POSIX/XSIiconv
. The macro checks for linker options needed to use iconv and appends them to theLIBINTL
andLTLIBINTL
variables.
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